基础工程思考题附（附答案）

复习思考题一、名词解释1、土的可松性：天然土经开挖后，其体积因松散而增加，虽经振动夯实，仍不能恢复原来体积的性质。

土的最初可松性系数: 自然状态下的土,经开挖后,其体积因松散而增加,以后虽经回填压实,仍不能恢复成原来的体积, 土经开挖后松散状态下的体积与土在自然状态下的体积之比称为土的最终可松性系数。

土的最终可松性系数: 自然状态下的土,经开挖后,其体积因松散而增加,以后虽经回填压实,仍不能恢复成原来的体积, 土经回填压实后压实状态下的体积与土在自然状态下的体积之比称为土的最终可松性系数。

土的干密度：是指单位体积土中固体颗粒的质量，即土体孔隙内无水时的单位土重。

干密度在一定程度上反映了土颗粒排列的紧密程度，可用来作为填土压实质量的控制指标。

最佳含水量：在压实机械和压实遍数相同的条件下,使填土压实获得最大密实度时土的含水量。

硫砂现象：采用集水坑降水法开挖基坑，当基坑开挖至地下水位以下时，有时坑底土会进入流动状态，随地下水涌入基坑，这种现象称为流砂现象。

集水坑降水：是在基坑的开挖过程中,沿坑底周围或中央挖有一定坡度的排水沟,在坑底每隔一定距离设一个集水坑,地下水通过排水沟流入集水坑中,然后用水泵抽出坑外。

井点降水：即在基坑开挖前，预先在基坑四周埋设一定数量的滤水管（井），在基坑（槽）开挖前和开挖过程中，从管（井）内不间断抽水排出，从而其四周地下水位降低至基坑（槽）以下，使所挖的土始终保持干燥状态，直至基础工程施工完毕为止。

2、锤击沉桩：也称打入桩，是利用桩锤下落产生的冲击能量将桩沉入土中。

静力压桩：就是利用压桩机架的自重和配重的静压力将预制桩压入土中的沉桩方法。

端承桩：是指桩尖位于坚硬、硬塑的粘土、碎石土、中密以上的砂土或风化岩等土层，在施工时，以贯入度为主，桩尖进入持力层深度或桩尖标高可作为参考。

摩擦桩: 是指桩尖位于软土层，在施工时，以桩尖设计标高控制为主，贯入度可作参考。

3、三²一砌筑法：即一铲灰、一块砖、一挤揉，并随手将挤出的砂浆刮去的砌筑方法。

自测题及思考题1 土方工程一、单项选择题1、以下哪项不属于常见的土方工程 A 。

A、人工挖孔灌注桩B、场地平整C、沟槽开挖与回填D、深基坑开挖2、在土方施工中，根据土的和将土分为八类。

( A )A、坚硬程度/开挖方法B、相对密实度/含水量C、密实度/可松性系数D、坚硬程度/含水量3、土的天然含水量，反映了土的干湿程度，按下式 B 计算。

A、W=m/v。

B、W=m W /m s×100%。

C、n=V v/V×100%。

D、K=V3/V1。

4、关于深基坑开挖下列说法明显错误的是 B 。

A、分层开挖、严禁超挖B、开槽支撑、先挖后撑C、坑底防浸水D、尽快浇筑基础垫层5、土方边坡可做成直壁不加支撑，根据判断，碎石土、可塑粉土、可塑粘性土和坚硬粘土，将它们做成直壁最大限制深度，正确的数据排列应该是 B 。

A、2.0/1.5/1.25/1.0mB、1.0/1.25/1.5/2.0mC、1.0/2.0/1.25/1.5mD、1.0/1.5/2.0/1.0m6、土方边坡的稳定，主要是由于 B 。

A、毛细水作用B、土颗粒间摩阻力和粘聚力C、重力D、重力和粘聚力7、以下不属于常用基坑坡面保护法的是 C 。

A、挂网抹面B、薄膜覆盖C、早拆模板D、喷射砼8、反铲挖土机的工作特点是 C 。

A、后退向下，自重切土B、前进向上，强制切土C、后退向下，强制切土D、直上直下，自重切土9、关于填土压实效果，正确的描述是 D 。

A．压实功越大越好。

机械碾压应6遍以上；B．压实功适当的前提下，填土含水量保持在20%以上；C．压实功适当的情况下，含水量越低越好，尤其是粉粘土；D．压实功适当的前提下，不同的土有相应的最佳含水量。

10、开挖深基坑时，如果分层设置多级平台，每层平台宽度不宜小于 C 米。

A、3B、10C、1、5D、511、边坡开挖应该尽量沿等高线 A 开挖。

A、自上而下，分层分段开挖B、自下而上，分层分段开挖C、整体开挖，全面展开D、自上而下，整体开挖12、开挖高度大于2米的干燥基坑，宜选用 D 。

第2章桩基工程一、思考题：2.1预制砼桩的制作、起吊、运输与堆放有哪些基本要求？2.2桩锤有哪些类型？工程中如何选择锤重？2.3简述打桩方法与质量控制标准。

2.4预制桩的沉桩方法有哪些？2.5泥浆护壁钻孔灌注桩的泥浆有何作用？泥浆循环有哪两种方式，其效果如何？2.6套管成孔灌注桩的施工流程如何？复打法应注意哪些问题？2.7试述地下连续墙施工过程。

2.8回转钻孔灌注桩泥浆正、反循环的主要差别是什么？分别适用什么条件？二、名词解释：⑴最后贯入度：⑵重锤低击：⑶复打法：⑷砼充盈系数：⑸正循环回转钻机成孔：三、选择题：1．单项选择题（每题的备选答案中，只有一个最符合题意）⑴当砼预制桩的设计间距大于4倍桩直径（或边长）时，宜采用的打桩顺序为（）。

A．逐排打设B．自中间向四周打设C．自四周向中间打设D．ABC均可⑵摩擦桩型的预制桩在沉桩时，主要质量控制指标是（）。

A．最后贯入度B．设计标高C．垂直度D．平面位置⑶在周围建筑物密集的狭窄场地施工大直径砼灌注桩，较宜采用（）。

A．钻孔灌注桩B．沉管灌注桩C．人工挖孔灌注桩D．爆扩灌注桩⑷砼灌注桩按成孔方法可分为以下四类：①钻孔灌注桩；②沉管灌注桩；③人工挖孔灌注桩；④爆扩灌注桩。

其中，属于挤土成孔的为（）。

A．①和②B．③和④C．①和③D．②和④⑸以下关于振动灌注桩的说法，正确的是（）。

A．适用范围广，除软土和新填土，其他各种土层均可适用B．单打法、反插法和复打法三种方法产生的桩承载能力依次上升C．振动灌注桩的承载能力比同样条件的钻孔灌注桩高D．其施工方法是用落锤将桩管打入土中成孔，然后放入钢筋骨架，灌注混凝土，拔出桩管成桩。

⑹桥梁墩台基础遇到砂夹卵石层的地层时，其桩体的施工方法有（）。

A．射水沉桩B．锤击沉桩C．振动沉桩D．静力压桩⑺地下连续墙施工技术所具有的优点是（）。

A．土方量小B．施工技术要求低C．接头质量较易控制D．墙面较平整⑻主要用于砂土、砂质粘土、亚粘土层，在含水砂层中效果更为显著的是（）。

《材料科学与工程基础》英文习题及思考题及答案第二章习题和思考题Questions and Problems2.6 Allowed values for the quantum numbers ofelectrons are as follows:The relationships between n and the shell designationsare noted in Table 2.1.Relative tothe subshells,l ＝0 corresponds to an s subshelll ＝1 corresponds to a p subshelll ＝2 corresponds to a d subshelll ＝3 corresponds to an f subshellFor the K shell, the four quantum numbersfor each of the two electrons in the 1s state, inthe order of nlmlms , are 100(1/2 ) and 100(-1/2 ).Write the four quantum numbers for allof the electrons inthe L and M shells, and notewhich correspond to the s, p, and d subshells.2.7 Give the electron configurations for the followingions: Fe2+, Fe3+, Cu+, Ba2+,Br-, andS2-.2.17 (a) Briefly cite the main differences betweenionic, covalent, and metallicbonding.(b) State the Pauli exclusion principle.2.18 Offer an explanation as to why covalently bonded materials are generally lessdense than ionically or metallically bonded ones.2.19 Compute the percents ionic character of the interatomic bonds for the followingcompounds: TiO2 , ZnTe, CsCl, InSb, and MgCl2 .2.21 Using Table 2.2, determine the number of covalent bonds that are possible foratoms of the following elements: germanium, phosphorus, selenium, and chlorine.2.24 On the basis of the hydrogen bond, explain the anomalous behavior of waterwhen it freezes. That is, why is there volume expansion upon solidification?3.1 What is the difference between atomic structure and crystal structure?3.2 What is the difference between a crystal structure and a crystal system?3.4Show for the body-centered cubic crystal structure that the unit cell edge lengtha and the atomic radius R are related through a =4R/√3.3.6 Show that the atomic packing factor for BCC is 0.68. .3.27* Show that the minimum cation-to-anion radius ratio for a coordinationnumber of 6 is 0.414. Hint: Use the NaCl crystal structure (Figure 3.5), and assume that anions and cations are just touching along cube edges and across face diagonals.3.48 Draw an orthorhombic unit cell, and within that cell a [121] direction and a(210) plane.3.50 Here are unit cells for two hypothetical metals:(a)What are the indices for the directions indicated by the two vectors in sketch(a)?(b) What are the indices for the two planes drawn in sketch (b)?3.51* Within a cubic unit cell, sketch the following directions:.3.53 Determine the indices for the directions shown in the following cubic unit cell:3.57 Determine the Miller indices for the planesshown in the following unit cell:3.58Determine the Miller indices for the planes shown in the following unit cell: 3.61* Sketch within a cubic unit cell the following planes:3.62 Sketch the atomic packing of (a) the (100)plane for the FCC crystal structure, and (b) the (111) plane for the BCC crystal structure (similar to Figures 3.24b and 3.25b).3.77 Explain why the properties of polycrystalline materials are most oftenisotropic.5.1 Calculate the fraction of atom sites that are vacant for lead at its meltingtemperature of 327_C. Assume an energy for vacancy formation of 0.55eV/atom.5.7 If cupric oxide (CuO) is exposed to reducing atmospheres at elevatedtemperatures, some of the Cu2_ ions will become Cu_.(a) Under these conditions, name one crystalline defect that you would expect toform in order to maintain charge neutrality.(b) How many Cu_ ions are required for the creation of each defect?5.8 Below, atomic radius, crystal structure, electronegativity, and the most commonvalence are tabulated, for several elements; for those that are nonmetals, only atomic radii are indicated.Which of these elements would you expect to form the following with copper:(a) A substitutional solid solution having complete solubility?(b) A substitutional solid solution of incomplete solubility?(c) An interstitial solid solution?5.9 For both FCC and BCC crystal structures, there are two different types ofinterstitial sites. In each case, one site is larger than the other, which site isnormally occupied by impurity atoms. For FCC, this larger one is located at the center of each edge of the unit cell; it is termed an octahedral interstitial site. On the other hand, with BCC the larger site type is found at 0, __, __ positions—that is, lying on _100_ faces, and situated midway between two unit cell edges on this face and one-quarter of the distance between the other two unit cell edges; it is termed a tetrahedral interstitial site. For both FCC and BCC crystalstructures, compute the radius r of an impurity atom that will just fit into one of these sites in terms of the atomic radius R of the host atom.5.10 (a) Suppose that Li2O is added as an impurity to CaO. If the Li_ substitutes forCa2_, what kind of vacancies would you expect to form? How many of thesevacancies are created for every Li_ added?(b) Suppose that CaCl2 is added as an impurity to CaO. If the Cl_ substitutes forO2_, what kind of vacancies would you expect to form? How many of thevacancies are created for every Cl_ added?5.28 Copper and platinum both have the FCC crystal structure and Cu forms asubstitutional solid solution for concentrations up to approximately 6 wt% Cu at room temperature. Compute the unit cell edge length for a 95 wt% Pt-5 wt% Cu alloy.5.29 Cite the relative Burgers vector–dislocation line orientations for edge, screw, andmixed dislocations.6.1 Briefly explain the difference between selfdiffusion and interdiffusion.6.3 (a) Compare interstitial and vacancy atomic mechanisms for diffusion.(b) Cite two reasons why interstitial diffusion is normally more rapid thanvacancy diffusion.6.4 Briefly explain the concept of steady state as it applies to diffusion.6.5 (a) Briefly explain the concept of a driving force.(b) What is the driving force for steadystate diffusion?6.6Compute the number of kilograms of hydrogen that pass per hour through a5-mm thick sheet of palladium having an area of 0.20 m2at 500℃. Assume a diffusion coefficient of 1.0×10- 8 m2/s, that the concentrations at the high- and low-pressure sides of the plate are 2.4 and 0.6 kg of hydrogen per cubic meter of palladium, and that steady-state conditions have been attained.6.7 A sheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200℃and is permitted to achieve a steady-state diffusion condition. The diffusion coefficient for nitrogen in steel at this temperature is 6×10-11m2/s, and the diffusion flux is found to be 1.2×10- 7kg/m2-s. Also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 4 kg/m3. How far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3?Assume a linear concentration profile.6.24. Carbon is allowed to diffuse through a steel plate 15 mm thick. Theconcentrations of carbon at the two faces are 0.65 and 0.30 kg C/m3 Fe, whichare maintained constant. If the preexponential and activation energy are 6.2 _10_7 m2/s and 80,000 J/mol, respectively, compute the temperature at which the diffusion flux is 1.43 _ 10_9 kg/m2-s.6.25 The steady-state diffusion flux through a metal plate is 5.4_10_10 kg/m2-s at atemperature of 727_C (1000 K) and when the concentration gradient is _350kg/m4. Calculate the diffusion flux at 1027_C (1300 K) for the sameconcentration gradient and assuming an activation energy for diffusion of125,000 J/mol.10.2 What thermodynamic condition must be met for a state of equilibrium to exist? 10.4 What is the difference between the states of phase equilibrium and metastability?10.5 Cite the phases that are present and the phase compositions for the followingalloys:(a) 90 wt% Zn–10 wt% Cu at 400℃(b) 75 wt% Sn–25wt%Pb at 175℃(c) 55 wt% Ag–45 wt% Cu at 900℃(d) 30 wt% Pb–70 wt% Mg at 425℃(e) 2.12 kg Zn and 1.88 kg Cu at 500℃(f ) 37 lbm Pb and 6.5 lbm Mg at 400℃(g) 8.2 mol Ni and 4.3 mol Cu at 1250℃.(h) 4.5 mol Sn and 0.45 mol Pb at 200℃10.6 For an alloy of composition 74 wt% Zn–26 wt% Cu, cite the phases presentand their compositions at the following temperatures: 850℃, 750℃, 680℃, 600℃, and 500℃.10.7 Determine the relative amounts (in terms of mass fractions) of the phases forthe alloys and temperatures given inProblem 10.5.10.9 Determine the relative amounts (interms of volume fractions) of the phases forthe alloys and temperatures given inProblem 10.5a, b, and c. Below are given theapproximate densities of the various metalsat the alloy temperatures:10.18 Is it possible to have a copper–silveralloy that, at equilibrium, consists of a _ phase of composition 92 wt% Ag–8wt% Cu, and also a liquid phase of composition 76 wt% Ag–24 wt% Cu? If so, what will be the approximate temperature of the alloy? If this is not possible,explain why.10.20 A copper–nickel alloy of composition 70 wt% Ni–30 wt% Cu is slowly heatedfrom a temperature of 1300_C .(a) At what temperature does the first liquid phase form?(b) What is the composition of this liquid phase?(c) At what temperature does complete melting of the alloy occur?(d) What is the composition of the last solid remaining prior to completemelting?10.28 .Is it possible to have a copper–silver alloy of composition 50 wt% Ag–50 wt%Cu, which, at equilibrium, consists of _ and _ phases having mass fractions W_ _0.60 and W_ _ 0.40? If so, what will be the approximate temperature of the alloy?If such an alloy is not possible, explain why.10.30 At 700_C , what is the maximum solubility (a) of Cu in Ag? (b) Of Ag in Cu?第三章习题和思考题3.3If the atomic radius of aluminum is 0.143nm, calculate the volume of its unitcell in cubic meters.3.8 Iron has a BCC crystal structure, an atomic radius of 0.124 nm, and an atomicweight of 55.85 g/mol. Compute and compare its density with the experimental value found inside the front cover.3.9 Calculate the radius of an iridium atom given that Ir has an FCC crystal structure,a density of 22.4 g/cm3, and an atomic weight of 192.2 g/mol.3.13 Using atomic weight, crystal structure, and atomic radius data tabulated insidethe front cover, compute the theoretical densities of lead, chromium, copper, and cobalt, and then compare these values with the measured densities listed in this same table. The c/a ratio for cobalt is 1.623.3.15 Below are listed the atomic weight, density, and atomic radius for threehypothetical alloys. For each determine whether its crystal structure is FCC,BCC, or simple cubic and then justify your determination. A simple cubic unitcell is shown in Figure 3.40.3.21 This is a unit cell for a hypotheticalmetal:(a) To which crystal system doesthis unit cell belong?(b) What would this crystal structure be called?(c) Calculate the density of the material, given that its atomic weight is 141g/mol.3.25 For a ceramic compound, what are the two characteristics of the component ionsthat determine the crystal structure?3.29 On the basis of ionic charge and ionic radii, predict the crystal structures for thefollowing materials: (a) CsI, (b) NiO, (c) KI, and (d) NiS. Justify your selections.3.35 Magnesium oxide has the rock salt crystal structure and a density of 3.58 g/cm3.(a) Determine the unit cell edge length. (b) How does this result compare withthe edge length as determined from the radii in Table 3.4, assuming that theMg2_ and O2_ ions just touch each other along the edges?3.36 Compute the theoretical density of diamond given that the CUC distance andbond angle are 0.154 nm and 109.5°, respectively. How does this value compare with the measured density?3.38 Cadmium sulfide (CdS) has a cubic unit cell, and from x-ray diffraction data it isknown that the cell edge length is 0.582 nm. If the measured density is 4.82 g/cm3 , how many Cd 2+ and S 2—ions are there per unit cell?3.41 A hypothetical AX type of ceramic material is known to have a density of 2.65g/cm 3 and a unit cell of cubic symmetry with a cell edge length of 0.43 nm. The atomic weights of the A and X elements are 86.6 and 40.3 g/mol, respectively.On the basis of this information, which of the following crystal structures is (are) possible for this material: rock salt, cesium chloride, or zinc blende? Justify your choice(s).3.42 The unit cell for Mg Fe2O3 (MgO-Fe2O3) has cubic symmetry with a unit celledge length of 0.836 nm. If the density of this material is 4.52 g/cm 3 , compute its atomic packing factor. For this computation, you will need to use ionic radii listed in Table 3.4.3.44 Compute the atomic packing factor for the diamond cubic crystal structure(Figure 3.16). Assume that bonding atoms touch one another, that the angle between adjacent bonds is 109.5°, and that each atom internal to the unit cell is positioned a/4 of the distance away from the two nearest cell faces (a is the unit cell edge length).3.45 Compute the atomic packing factor for cesium chloride using the ionic radii inTable 3.4 and assuming that the ions touch along the cube diagonals.3.46 In terms of bonding, explain why silicate materials have relatively low densities.3.47 Determine the angle between covalent bonds in an SiO44—tetrahedron.3.63 For each of the following crystal structures, represent the indicated plane in themanner of Figures 3.24 and 3.25, showing both anions and cations: (a) (100)plane for the rock salt crystal structure, (b) (110) plane for the cesium chloride crystal structure, (c) (111) plane for the zinc blende crystal structure, and (d) (110) plane for the perovskite crystal structure.3.66 The zinc blende crystal structure is one that may be generated from close-packedplanes of anions.(a) Will the stacking sequence for this structure be FCC or HCP? Why?(b) Will cations fill tetrahedral or octahedral positions? Why?(c) What fraction of the positions will be occupied?3.81* The metal iridium has an FCC crystal structure. If the angle of diffraction forthe (220) set of planes occurs at 69.22°(first-order reflection) when monochromatic x-radiation having a wavelength of 0.1542 nm is used, compute(a) the interplanar spacing for this set of planes, and (b) the atomic radius for aniridium atom.4.10 What is the difference between configuration and conformation in relation topolymer chains? vinyl chloride).4.22 (a) Determine the ratio of butadiene to styrene mers in a copolymer having aweight-average molecular weight of 350,000 g/mol and weight-average degree of polymerization of 4425.(b) Which type(s) of copolymer(s) will this copolymer be, considering thefollowing possibilities: random, alternating, graft, and block? Why?4.23 Crosslinked copolymers consisting of 60 wt% ethylene and 40 wt% propylenemay have elastic properties similar to those for natural rubber. For a copolymer of this composition, determine the fraction of both mer types.4.25 (a) Compare the crystalline state in metals and polymers.(b) Compare thenoncrystalline state as it applies to polymers and ceramic glasses.4.26 Explain briefly why the tendency of a polymer to crystallize decreases withincreasing molecular weight.4.27* For each of the following pairs of polymers, do the following: (1) state whetheror not it is possible to determine if one polymer is more likely to crystallize than the other; (2) if it is possible, note which is the more likely and then cite reason(s) for your choice; and (3) if it is not possible to decide, then state why.(a) Linear and syndiotactic polyvinyl chloride; linear and isotactic polystyrene.(b) Network phenol-formaldehyde; linear and heavily crosslinked ci s-isoprene.(c) Linear polyethylene; lightly branched isotactic polypropylene.(d) Alternating poly(styrene-ethylene) copolymer; randompoly(vinylchloride-tetrafluoroethylene) copolymer.4.28 Compute the density of totally crystalline polyethylene. The orthorhombic unitcell for polyethylene is shown in Figure 4.10; also, the equivalent of two ethylene mer units is contained within each unit cell.5.11 What point defects are possible for MgO as an impurity in Al2O3? How manyMg 2+ ions must be added to form each of these defects?5.13 What is the composition, in weight percent, of an alloy that consists of 6 at% Pband 94 at% Sn?5.14 Calculate the composition, in weight per-cent, of an alloy that contains 218.0 kgtitanium, 14.6 kg of aluminum, and 9.7 kg of vanadium.5.23 Gold forms a substitutional solid solution with silver. Compute the number ofgold atoms per cubic centimeter for a silver-gold alloy that contains 10 wt% Au and 90 wt% Ag. The densities of pure gold and silver are 19.32 and 10.49 g/cm3 , respectively.8.53 In terms of molecular structure, explain why phenol-formaldehyde (Bakelite)will not be an elastomer.10.50 Compute the mass fractions of αferrite and cementite in pearlite. assumingthat pressure is held constant.10.52 (a) What is the distinction between hypoeutectoid and hypereutectoid steels?(b) In a hypoeutectoid steel, both eutectoid and proeutectoid ferrite exist. Explainthe difference between them. What will be the carbon concentration in each?10.56 Consider 1.0 kg of austenite containing 1.15 wt% C, cooled to below 727_C(a) What is the proeutectoid phase?(b) How many kilograms each of total ferrite and cementite form?(c) How many kilograms each of pearlite and the proeutectoid phase form?(d) Schematically sketch and label the resulting microstructure.10.60 The mass fractions of total ferrite and total cementite in an iron–carbon alloyare 0.88 and 0.12, respectively. Is this a hypoeutectoid or hypereutectoid alloy?Why?10.64 Is it possible to have an iron–carbon alloy for which the mass fractions of totalferrite and proeutectoid cementite are 0.846 and 0.049, respectively? Why orwhy not?第四章习题和思考题7.3 A specimen of aluminum having a rectangular cross section 10 mm _ 12.7 mmis pulled in tension with 35,500 N force, producing only elastic deformation. 7.5 A steel bar 100 mm long and having a square cross section 20 mm on an edge ispulled in tension with a load of 89,000 N , and experiences an elongation of 0.10 mm . Assuming that the deformation is entirely elastic, calculate the elasticmodulus of the steel.7.7 For a bronze alloy, the stress at which plastic deformation begins is 275 MPa ,and the modulus of elasticity is 115 Gpa .(a) What is the maximum load that may be applied to a specimen with across-sectional area of 325mm, without plastic deformation?(b) If the original specimen length is 115 mm , what is the maximum length towhich it may be stretched without causing plastic deformation?7.8 A cylindrical rod of copper (E _ 110 GPa, Stress (MPa) ) having a yield strengthof 240Mpa is to be subjected to a load of 6660 N. If the length of the rod is 380 mm, what must be the diameter to allow an elongation of 0.50 mm?7.9 Consider a cylindrical specimen of a steel alloy (Figure 7.33) 10mm in diameterand 75 mm long that is pulled in tension. Determine its elongation when a load of 23,500 N is applied.7.16 A cylindrical specimen of some alloy 8 mm in diameter is stressed elasticallyin tension. A force of 15,700 N produces a reduction in specimen diameter of 5 _ 10_3 mm. Compute Poisson’s ratio for this material if its modulus of elasticity is 140 GPa .7.17 A cylindrical specimen of a hypothetical metal alloy is stressed in compression.If its original and final diameters are 20.000 and 20.025 mm, respectively, and its final length is 74.96 mm, compute its original length if the deformation is totally elastic. The elastic and shear moduli for this alloy are 105 Gpa and 39.7 GPa,respectively.7.19 A brass alloy is known to have a yield strength of 275 MPa, a tensile strength of380 MPa, and an elastic modulus of 103 GPa . A cylindrical specimen of thisalloy 12.7 mm in diameter and 250 mm long is stressed in tension and found to elongate 7.6 mm . On the basis of the information given, is it possible tocompute the magnitude of the load that is necessary to produce this change inlength? If so, calculate the load. If not, explain why.7.20A cylindrical metal specimen 15.0mmin diameter and 150mm long is to besubjected to a tensile stress of 50 Mpa; at this stress level the resulting deformation will be totally elastic.(a)If the elongation must be less than 0.072mm,which of the metals in Tabla7.1are suitable candidates? Why ?(b)If, in addition, the maximum permissible diameter decrease is 2.3×10-3mm,which of the metals in Table 7.1may be used ? Why?7.22 Cite the primary differences between elastic, anelastic, and plastic deformationbehaviors.7.23 diameter of 10.0 mm is to be deformed using a tensile load of 27,500 N. It mustnot experience either plastic deformation or a diameter reduction of more than7.5×10-3 mm. Of the materials listed as follows, which are possible candidates?Justify your choice(s).7.24 A cylindrical rod 380 mm long, having a diameter of 10.0 mm, is to besubjected to a tensile load. If the rod is to experience neither plastic deformationnor an elongation of more than 0.9 mm when the applied load is 24,500 N,which of the four metals or alloys listed below are possible candidates?7.25 Figure 7.33 shows the tensile engineering stress–strain behavior for a steel alloy.(a) What is the modulus of elasticity?(b) What is the proportional limit?(c) What is the yield strength at a strain offset of 0.002?(d) What is the tensile strength?7.27 A load of 44,500 N is applied to a cylindrical specimen of steel (displaying thestress–strain behavior shown in Figure 7.33) that has a cross-sectional diameter of 10 mm .(a) Will the specimen experience elastic or plastic deformation? Why?(b) If the original specimen length is 500 mm), how much will it increase inlength when t his load is applied?7.29 A cylindrical specimen of aluminumhaving a diameter of 12.8 mm and a gaugelength of 50.800 mm is pulled in tension. Usethe load–elongation characteristics tabulatedbelow to complete problems a through f.(a)Plot the data as engineering stressversusengineering strain.(b) Compute the modulus of elasticity.(c) Determine the yield strength at astrainoffset of 0.002.(d) Determine the tensile strength of thisalloy.(e) What is the approximate ductility, in percent elongation?(f ) Compute the modulus of resilience.7.35 (a) Make a schematic plot showing the tensile true stress–strain behavior for atypical metal alloy.(b) Superimpose on this plot a schematic curve for the compressive truestress–strain behavior for the same alloy. Explain any difference between thiscurve and the one in part a.(c) Now superimpose a schematic curve for the compressive engineeringstress–strain behavior for this same alloy, and explain any difference between this curve and the one in part b.7.39 A tensile test is performed on a metal specimen, and it is found that a true plasticstrain of 0.20 is produced when a true stress of 575 MPa is applied; for the same metal, the value of K in Equation 7.19 is 860 MPa. Calculate the true strain that results from the application of a true stress of 600 Mpa.7.40 For some metal alloy, a true stress of 415 MPa produces a plastic true strain of0.475. How much will a specimen of this material elongate when a true stress of325 MPa is applied if the original length is 300 mm ? Assume a value of 0.25 for the strain-hardening exponent n.7.43 Find the toughness (or energy to cause fracture) for a metal that experiences bothelastic and plastic deformation. Assume Equation 7.5 for elastic deformation,that the modulus of elasticity is 172 GPa , and that elastic deformation terminates at a strain of 0.01. For plastic deformation, assume that the relationship between stress and strain is described by Equation 7.19, in which the values for K and n are 6900 Mpa and 0.30, respectively. Furthermore, plastic deformation occurs between strain values of 0.01 and 0.75, at which point fracture occurs.7.47 A steel specimen having a rectangular cross section of dimensions 19 mm×3.2mm (0.75in×0.125in.) has the stress–strain behavior shown in Figure 7.33. If this specimen is subjected to a tensile force of 33,400 N (7,500lbf ), then(a) Determine the elastic and plastic strain values.(b) If its original length is 460 mm (18 in.), what will be its final length after theload in part a is applied and then released?7.50 A three-point bending test was performed on an aluminum oxide specimenhaving a circular cross section of radius 3.5 mm; the specimen fractured at a load of 950 N when the distance between the support points was 50 mm . Another test is to be performed on a specimen of this same material, but one that has a square cross section of 12 mm length on each edge. At what load would you expect this specimen to fracture if the support point separation is 40 mm ?7.51 (a) A three-point transverse bending test is conducted on a cylindrical specimenof aluminum oxide having a reported flexural strength of 390 MPa . If the speci- men radius is 2.5 mm and the support point separation distance is 30 mm ,predict whether or not you would expect the specimen to fracture when a load of 620 N is applied. Justify your prediction.(b) Would you be 100% certain of the prediction in part a? Why or why not?7.57 When citing the ductility as percent elongation for semicrystalline polymers, it isnot necessary to specify the specimen gauge length, as is the case with metals.Why is this so?7.66 Using the data represented in Figure 7.31, specify equations relating tensilestrength and Brinell hardness for brass and nodular cast iron, similar toEquations 7.25a and 7.25b for steels.8.4 For each of edge, screw, and mixed dislocations, cite the relationship between thedirection of the applied shear stress and the direction of dislocation line motion.8.5 (a) Define a slip system.(b) Do all metals have the same slip system? Why or why not?8.7. One slip system for theBCCcrystal structure is _110__111_. In a manner similarto Figure 8.6b sketch a _110_-type plane for the BCC structure, representingatom positions with circles. Now, using arrows, indicate two different _111_ slip directions within this plane.8.15* List four major differences between deformation by twinning and deformationby slip relative to mechanism, conditions of occurrence, and final result.8.18 Describe in your own words the three strengthening mechanisms discussed inthis chapter (i.e., grain size reduction, solid solution strengthening, and strainhardening). Be sure to explain how dislocations are involved in each of thestrengthening techniques.8.19 (a) From the plot of yield strength versus (grain diameter)_1/2 for a 70 Cu–30 Zncartridge brass, Figure 8.15, determine values for the constants _0 and ky inEquation 8.5.(b) Now predict the yield strength of this alloy when the average grain diameteris 1.0 _ 10_3 mm.8.20. The lower yield point for an iron that has an average grain diameter of 5 _ 10_2mm is 135 MPa . At a grain diameter of 8 _ 10_3 mm, the yield point increases to 260MPa. At what grain diameter will the lower yield point be 205 Mpa ?8.24 (a) Show, for a tensile test, thatif there is no change in specimen volume during the deformation process (i.e., A0 l0 _Ad ld).(b) Using the result of part a, compute the percent cold work experienced bynaval brass (the stress–strain behavior of which is shown in Figure 7.12) when a stress of 400 MPa is applied.8.25 Two previously undeformed cylindrical specimens of an alloy are to be strainhardened by reducing their cross-sectional areas (while maintaining their circular cross sections). For one specimen, the initial and deformed radii are 16 mm and11 mm, respectively. The second specimen, with an initial radius of 12 mm, musthave the same deformed hardness as the first specimen; compute the secondspecimen’s radius after deformation.8.26 Two previously undeformed specimens of the same metal are to be plasticallydeformed by reducing their cross-sectional areas. One has a circular cross section, and the other is rectangular is to remain as such. Their original and deformeddimensions are as follows:Which of these specimens will be the hardest after plastic deformation, and why?8.27 A cylindrical specimen of cold-worked copper has a ductility (%EL) of 25%. Ifits coldworked radius is 10 mm (0.40 in.), what was its radius beforedeformation?8.28 (a) What is the approximate ductility (%EL) of a brass that has a yield strengthof 275 MPa ?(b) What is the approximate Brinell hardness of a 1040 steel having a yieldstrength of 690 MPa?8.41 In your own words, describe the mechanisms by which semicrystalline polymers(a) elasticallydeform and (b) plastically deform, and (c) by which elastomerselastically deform.8.42 Briefly explain how each of the following influences the tensile modulus of asemicrystallinepolymer and why:(a) molecular weight;(b) degree of crystallinity;(c) deformation by drawing;(d) annealing of an undeformed material;(e) annealing of a drawn material.8.43* Briefly explain how each of the following influences the tensile or yieldstrength of a semicrystalline polymer and why:(a) molecular weight;。

第一章1、什么是土的可松性？P2土的可松性是指自然状态下的土经过开挖后，其体积因松散而增加，以后虽经回填压实，仍不能恢复到原来的体积。

3、影响基坑放坡大小的因素是什么？土方边坡坡度：1/m==H/B；m=B/H坡度系数；B-坡度宽度；H--坡高度；影响基坑放坡的原因有以下几点：1、地质、水文状况和土质特性。

2、选择的施工方法（包括基坑护坡、土方开挖、降水等）。

3、采用的开挖工具5、只要求场地平整前后土方量相等，其设计标高如何计算？场地平整场要求场地内的土方在平整前和平整后相等，达到挖填土方量平衡，即“挖填平衡”的原则确定设计标高H。

P39、试述推土机、铲运机和正挖土机的施工方法。

P12推土机：可采用下坡推土、槽形推土以及并列推土等方法；铲运机：采用下坡铲土、跨铲法、推土机助铲法等；10、基坑降水方法有哪几种？各适用于何种情况？P14地下水处理方法有止水法和降水法；P14A.集水井降水（明沟排水）；B.轻型井点降水；C.喷射井点；D.电渗井点；E.管井井点；F.回灌井点。

11、什么是流砂现象？产生流砂的原因？流砂防治的具体措施有哪些？P14流砂现象：粒径很小、无塑性的土壤，在动水压力推动下，极易失去稳定，而随地下水一起流动涌入坑内，这种现象就称为流砂现象。

产生原因：内因：取决于土的性质，当上为细砂和粉砂时其土的孔隙比大、含水量大、粘粒含量少、粉粒多、渗透系数小、排水性能差等均可能产生流砂现象；外因：土体承受足够大的动水压力。

流砂会使土失去承载力，引起塌方，造成土边挖边冒，难以施工。

防治措施：枯水期施工、做止水帷幕、水中挖土、抢速度施工以及井点降水等，其中轻型井点降水法是根除流砂常用的有效方法。

15、用井点降水时，如何防止周围地面沉降？P19应对附近的建筑物进行沉降观测采取相应措施（加设回灌井点或设置止水帷幕以及减缓降水速度等方法），以防造成危害。

16、常用基坑支护结构有哪几种？各适用于何种情况？P23.表1-1217、施工时注意事项主要有：1、保证基底土不受扰动；2、放暴晒，水浸泡；3、验槽；4、回填土应及时；19、基坑有哪几种常用的挖土方式？各有何优缺点？P3421、土方填筑宜用哪些土体？P36.22、简述基坑土的填筑方法。

自测题及思考题1 土方工程一、单项选择题1、以下哪项不属于常见的土方工程 A 。

A、人工挖孔灌注桩B、场地平整C、沟槽开挖与回填D、深基坑开挖2、在土方施工中，根据土的和将土分为八类。

( A )A、坚硬程度/开挖方法B、相对密实度/含水量C、密实度/可松性系数D、坚硬程度/含水量3、土的天然含水量，反映了土的干湿程度，按下式 B 计算。

A、W=m/v。

B、W=m W /m s×100%。

C、n=V v/V×100%。

D、K=V3/V1。

4、关于深基坑开挖下列说法明显错误的是 B 。

A、分层开挖、严禁超挖B、开槽支撑、先挖后撑C、坑底防浸水D、尽快浇筑基础垫层5、土方边坡可做成直壁不加支撑，根据判断，碎石土、可塑粉土、可塑粘性土和坚硬粘土，将它们做成直壁最大限制深度，正确的数据排列应该是 B 。

A、2.0/1.5/1.25/1.0mB、1.0/1.25/1.5/2.0mC、1.0/2.0/1.25/1.5mD、1.0/1.5/2.0/1.0m6、土方边坡的稳定，主要是由于 B 。

A、毛细水作用B、土颗粒间摩阻力和粘聚力C、重力D、重力和粘聚力7、以下不属于常用基坑坡面保护法的是 C 。

A、挂网抹面B、薄膜覆盖C、早拆模板D、喷射砼8、反铲挖土机的工作特点是 C 。

A、后退向下，自重切土B、前进向上，强制切土C、后退向下，强制切土D、直上直下，自重切土9、关于填土压实效果，正确的描述是 D 。

A．压实功越大越好。

机械碾压应6遍以上；B．压实功适当的前提下，填土含水量保持在20%以上；C．压实功适当的情况下，含水量越低越好，尤其是粉粘土；D．压实功适当的前提下，不同的土有相应的最佳含水量。

10、开挖深基坑时，如果分层设置多级平台，每层平台宽度不宜小于 C 米。

A、3B、10C、1、5D、511、边坡开挖应该尽量沿等高线 A 开挖。

A、自上而下，分层分段开挖B、自下而上，分层分段开挖C、整体开挖，全面展开D、自上而下，整体开挖12、开挖高度大于2米的干燥基坑，宜选用 D 。

答：路基：路基是在天然地表面按照道路的设计线形(位置)和设计横断面(几何尺寸)的要求开挖或者堆填而成的岩土结构物。

路面：路面是在路基顶面的行车部份用各种混合料铺筑而成的层状结构物。

作用：路基是路面结构的基础，坚固而又稳定的路基为路面结构长期承受汽车荷载提供了重要的保证，而路面结构层的存在又保护了路基，使之避免了直接经受车辆和大气的破坏作用，长期处于稳定状态。

基本性能要求:①承载能力(包括强度和刚度)；②稳定性；③耐久性；④表面平整度；⑤表面抗滑性能。

答：①地理条件；②地质条件；③气候条件；④水文和水文地质条件；⑤土的类别。

答：我国公路用土依据土的颗粒组成特征，土的塑性指标和土中有机质存在的情况，分为巨粒土、粗粒土、细粒土和特殊土四类。

答：我国地域辽阔，又是一个多山的国家，从北到南分处于寒带、温带和热带。

从青藏高原到东部沿海高程相差 4000m 以上，因此自然因素变化极其复杂。

不同地区自然条件的差异同公路建设有密切关系。

为了区分各地自然区域的筑路特性，进行了公路自然区划。

原则：①道路工程特征相似的原则；②地表气候区划差异性的原则；③自然气候因素既有综合又有主导作用的原则。

答：①大气降水；②地面水；③地下水；④毛细水；⑤水蒸气凝结水；⑥薄膜移动水。

答：沿路基深度浮现较大的温度梯度时，水分在温差的影响下以液态或者气态由热处向冷处挪移，并积聚在该处，积聚的水冻结后体积增大，使路基拱起而造成面层开裂，使路面遭受严重破坏答：分为四类，干燥、中湿、潮湿和过湿。

要求：路基保持干燥或者中湿状态。

答：按不利季节路槽底面以下 80cm 深度内土的平均稠度确定。

答：用路基临界高度作为判别标准。

答：稠度 w 定义为土的含水率 w 与土的液限 w 之差与土的塑限 w 和液限 w 之差C L P L的比值。

答：与分界稠度相对应的路基离地下水或者地表积水水位的高度称为路基临界高度 H。

答：由行车道、硬路肩和土路肩组成。

通常分为槽式横断面和全铺式横断面。

第一篇土木工程施工技术第一章土石方工程1、土的可松性系数在土方工程中有哪些具体应用？答：土的可松性对确定场地设计标高、土方量的平衡调配、计算运土机具的数量和弃土坑的容积，以及计算填方所需的挖方体积等均有很大影响。

2、试述影响边坡稳定性的因素有哪些？并说明原因？答： a.土质，土质粘聚力越大边坡越稳定，边坡可陡些；b.挖土深度，深度越大，产生滑移土体越重，边坡越不稳定；c.施工期边坡上的荷载，动荷载静荷载增加了边坡的剪应力；d.土的含水率及排水情况，土的含水率越大，土体自重增加土体抗剪强度下降；e.边坡留置时间，留置时间越长边坡越稳定。

3、水泥土墙设计应考虑哪些因素？水泥土搅拌桩施工应注意哪些问题？答：因素：水泥土墙设计应考虑哪些因素：墙背填土的粘聚力和内摩擦角大小、活荷载分布及大小、挡土墙的基底应力大小、挡土墙的结构形式和断面尺寸。

注意问题：水泥土搅拌桩施工中应注意水泥浆配合比及搅拌速度、水泥浆喷射速率与提升速度的关系及每根桩的水泥浆喷注量，以保证注浆的均匀性与桩身强度。

施工中还应注意控制桩的垂直度以及桩的搭接等，以保证水泥土墙的整体性与抗渗性。

4、基坑土方开挖应遵循什么原则？针对不同的基坑应如何具体贯彻？答：原则; 开槽支撑，先撑后挖，分层开挖，严禁超挖。

开挖到坑底后垫层应随挖随浇。

（1）对于放坡和坑内无内支撑的基坑开挖：应严格分层开挖，当基坑面积较大时，应采取分块开挖，基坑分块开挖应尽可能利用后浇带，按后浇带设置分区，尽量避免基础结构因分块开挖而增设施工缝。

对于重力式水泥土墙，在平面上可采取盆式开挖。

对于土钉墙或桩锚结构，宜采用岛式开挖方法。

土方开挖后不应将土方堆放在坑边。

（2）对于由内支撑的基坑开挖：其土方开挖需要与支撑施工相协调，此外，为便于挖土作业，一般需在第一道支撑上设置栈桥，在支撑下布置小型挖土机。

在土质较好的基坑中，可根据条件设置临时坡道，但临时坡道必须稳定可靠，必要时对坡道下的土体进行加固或设置结构性坡道。