英语学习土力学问答题(共16页).doc

精选优质文档-倾情为你奉上Simple answer1, what is the difference between the normal consolidated clay and the over consolidated clay, the compression and the strength characteristics of the two?Answer: the soil in history has ever received the maximum effective stress for preconsolidation stress, expressed on the PC, and the force and the present Po 'than that of overconsolidation ratio (OCR), of the natural clay, OCR>1. The soil is overconsolidated; when the OCR = 1, normal consolidation soil preconsolidation stress. OCR=1 and the existing effective stress p '0 is less than the existing consolidation stress P0, the soil is less consolidated soilCompression characteristic difference: when the pressure increment is the same, the compression ratio of the normal consolidated soil is larger than that of the over consolidated soil.The strength characteristics are different: the strength of the super consolidated soil is higher than that of the normal consolidated soil.Shear properties: because the under consolidated soil is also a normal consolidated soil, so they have the same shear shape, that is, shear shrinkage and a positive pore water stress. Overconsolidated soil divided into strong overconsolidated soil and slightly over consolidated soil, ultra weak soil consolidation in the shear and normal consolidation soil as, volume dilation, produces a positive pore pressure, but pore water pressure to smaller than the normal consolidation soil; strong consolidation in the shearing process will produce dilatancy effect and produce negative pore water stress.2, the paper describes the factors affecting the soil compaction?A: the main factors of soil compaction are water content, compaction function, type and size of soil and coarse grain content.Of cohesive soil, moisture content influence is mainly manifested as when the moisture content is low. The same compaction function under the lower stem density, with increase of water content and the dry density will gradually improve; when reaching a certain moisture content, corresponding hit real function will get maximum dry density, corresponding water cut rate rate for optimum water content; with the increase of water content, maximum dry density but will decrease.The impact of compaction function shows that the larger the compaction function, the dry density of soil is larger, and the optimal water content decreases with the increase of compaction function.Soil type and gradation of influence performance in cohesive soil is usually no cohesive soil compressibility, high clay content, compressibility; good gradation, easy compaction, dry density high;The coarse grain content has influence on the compactness, and the results of the light compaction test need to be modified when the coarse grain content of more than 5mm grain size is more than 25% and 30%.3, compare the Rankine earth pressure theory and Kulun earth pressure theory and the similarities and differences of advantages and disadvantages.The same point: it is required that the retaining wall moves to make the shear strength of the soil filled after the wall to shear strength (limit state);Different points: Lang Ken theory is according to various points of soil in the equilibrium state of stress conditions for wall back on the earth pressure. Requirements for wall surface is smooth, and the filling surface level and result in too large. And Coulomb theory is according to the back of the wall and sliding surface of wedge type in the condition of static equilibrium in the limit equilibrium state for general earth pressure. The back wall can be tilted, rough soil surface tilt, calculation results of the initiative pressure meet the requirements, and passive pressure error larger. Rankine theory is considering the wall backfill per point of damage, up to the limit state; Coulomb theory consider sliding mass of the rigid body limit equilibrium;Rankine earth pressure theory has the advantages of simple formula, easy to use; disadvantages: of wall inclination, wall backfill surface tilt is not applicable;The theory of soil pressure in Kulun: it is applicable to the slope of the wall and the back fill slope of the wall; the disadvantage is that the condition of the clay is not considered;4, what are the foundations of the destruction of the form? What kind of soil foundation will happen to each of the soil? According to the theoretical calculation formula of bearing capacity, which is the main factor influencing the bearing capacity of shallow foundation? According to the theoretical formula to determine the bearing capacity which is applicable to the type of failure?Answer: the overall shear failure, shear failure and punching failure.Foundation failure mode mainly and soil properties especially related to compaction, in general, for solid or compacting the soil with low compressibility, usually presents general shear failure. For soft clay or loose sand foundation with high compressibility, often appear local shear failure or punching shear damage. Theoretical formula method, standard method and test method.Soil bulk density and strength index, foundation width b, foundation depth D, underground water level, etc. The bearing capacity determined by the theoretical formula is applicable to the whole shear failure mode.5, why is that in general, the soil's self weight stress will not cause the compression of the soil deformation (or settlement), and when the ground water level down, it will cause the soil to sink it?A: under normal circumstances, the foundation is a number of years of deposition, the weight of the role of stress has been reduced to a stable. Self weight stress has been transformed into the effective stress, and this kind of case, the self weight stress will not cause the soil to be compressed. But if the soil is recently deposited, the self weight stress has not completely changed the stress, then the self weight stress will be produced. (5 points)When the decline of groundwater level, soil from water under variable for the water and the soil original by the buoyancy effect. Now the Futuoliyin drawdown disappear, equivalent to exerting a downward volume force in the soil, its size is equal to the buoyant force. The force is bound to cause soil compression.6, how to measure the size distribution curve of soil and the frequency curve of grain size, what is the use? On the gradation of discontinuous soil, the two curves each have what characteristics?Answer: 1. Soil particle size distribution curve: with soil particle size of the abscissa (logarithmic scale) is less than the percentage of the total mass a particle size of soil quality for sample is plotted as the ordinate of the curve. According to the soil particle size distribution curve of the content of soil particle size fractions can be obtained for assessment of soil classification and general assessment of engineering properties. Some of the characteristics of particle size and for the quality of building materials selection and evaluation of soil gradation.The frequency curves of 2 groups: the average particle size of the particle group is the logarithmic scale, and the content of the soil particles in each particle group is plotted as the vertical coordinate.The particle size distribution curve of soil can not only determine the relative content of grain, but also can judge the gradation of soil according to the slope of the curve.7, other conditions in the same case, the settlement of the over consolidated clay must be less than the normal consolidation of clay settlement? Why? Answer: is. Compared with normal consolidated clay, overconsolidated clay pore Bibi normal consolidated soil is small, if the existing effective stress are the same, under a load increment, overconsolidated soil is along the recompression curve compression, and normally consolidated soils along the compression curve. Because of the same soil, the compression curve is more slowly than the compression curve, that is, the compression index is smaller than the compression index, therefore, the settlement of over consolidated clay is smaller than that of the normal consolidated soil.8, what is the principle of effective stress? In the figure, the foundation soil moisture is severe, the saturation is heavy and the float is heavy respectively, and the water is heavy, the water column of the M point of the measuring tube is high as shown in figure. The calculation formula of total stress, pore water stress, effective stress and self weight stress of M point are written.Answer: caused by external loads on the plane to the general stress for 6S, then it must by the surface force pore u and inter particle contact surface share, namely method on the surface to force equal to pore and interparticle undertaken by forces, namely the 6S = and '+ U.M point total stress:M point pore water stress:M point effective stress:M point self weight stress:9, the sliding surface slope slide which has several forms? What happened in the case? Safety coefficient of clay soil slope under the condition of no seepage can have what kinds of method? What are the methods used to analyze the stability of the slope?Answer: sliding surface slope slide are: arc, plane, composite sliding surface.Circular sliding usually occurs in a homogeneous clayey soil slope; sliding plane usually occurs in cohesionless soil; composite sliding surface in soil slope is not uniform slope.No seepage and clayey soil slope stability safety factor calculation method is: Phi = 0 analysis method, the Swedish division method, simplified Bishop method. In the slope stability analysis is often used method: Fellenius method, bishop strip method, Yang cloth strip method and imbalance thrust force method.10, the modified Terzaghi ultimate bearing capacity formula is suitable for what kind of failure types of foundation? The Terzaghi ultimate bearing capacity formula specify the position of the water table is how to influence on the bearing capacity?Answer: the modified Terzaghi formula of ultimate bearing capacity for strip foundation on the whole shear failure of foundation.Terzaghi's ultimate bearing capacity formula. Groundwater depth is greater, in the 1, 2 in the gamma were not affected; if the underground water level in the basement, 1 item of using gamma float density, reduce the carrying capacity of; if underground water level rose to ground at or above, the 1, 2 in the gamma were applied floating bulk density, capacity to further reduce.11, there are several kinds of clay soil? By what is the distinction between the status of the state?Answer: solid, semi solid, plastic, flow four states. (three can also be used) generally used to describe the degree of consistency of cohesive soil moisture (state) reflected in the moisture content of the effect of external forces and the ability to deform or damage.The states are distinguished as follows:Liquid limit (WL) - from the flow state change rate of plastic state boundaries of water, is plastic state of the maximum water content; plastic limit (WP) - the transition from plastic state for semi solid state limit moisture content is water in the lower plastic state rate;Shrinkage limit (Ws) - from the semi solid state to the boundary of the solid state water content, that is, with the reduction of soil moisture content and the volume began to change when the volume of water content.12, what is the pre consolidation pressure? What kind of soil is under consolidated soil? There is a certain excess pore water stress in the under consolidated soil layer. Under the consolidated soil, such as no new pressure, the soil will continue to compress it? Why?A: the pre consolidation pressure for the soil in the history of the maximum effective stress, with Pc. Under the action of self weight stress, the under consolidated soil is not fully consolidated, that is, the existing effective stress is less than the existing consolidation stress. There must be some excess pore water stress in the under consolidated soil. Because under the effect of self weight stress, under the self weight stress is not stable, and the attachment stress has not yet been converted to the effective stress, and there is still a part of the pore water. With the discharge of the pore water, the dissipation of the pore water stress, the ratio of the soil to the pore is further reduced, so that the soil layer will continue to compress even if no new pressure is applied.13, respectively, in the case of the flow below the two figure in the soil ABCDEA on the role of the force, and marked in the diagram. Among them, the map (a) to the soil as the research object, the map (b) to soil particles as the research object.Figure (a) (b)Answer:At. Taking into account gravity, taking into account the water pressure of ED and CD, considering the tangential reaction and normal reaction of AEDAt. Taking into account the gravity, considering the buoyancy, considering the seepage force. The tangential reaction and normal force on AED;14, the liquefaction of sand. (6 points)Answer: for saturated loose sand, when subjected to sudden dynamic load, because of the dynamic shear force should be to reduce the volume of the trend, because of the short time to wait outside the drainage, so the big pore water stress. According to the principle of effective stress, when the dynamic load caused by the excess pore water should u is reached, effective stress, the shear strength, cohesionless soil foundation will lose its bearing capacity, slope flow collapse.15, the sliding surface slope slide which has several forms? What happened in the case? The calculation method of stability coefficient of 3 kinds of lists of cohesive soil slope?Answer: sliding surface slope slide are: arc, plane, composite sliding surface. Circular sliding usually occurs in a homogeneous clayey soil slope; sliding plane usually occurs in cohesionless soil; composite sliding surface in soil slope is not uniform slope. Safety coefficient of clay soil slope calculation method: Phi = 0 analysis method, Sweden slice method and simplified Bishop method etc.16, the Yangtze River levee water retaining diagram as shown in Figure 2, respectively discuss flood peak arrive the river water level rose during and after the flood peak river water level dropped seepage function in the process of embankment retaining surface and back surface of the slope stability influence.Answer: the flood peak arrived, have toward seepage outside slope, theHave a favorable impact on water retaining slope stability, the dorsal surface of slopeStability adversely affected.After the flood peak water level decline, provided the water level in the above the river, have toward the seepage of the