Closed-form Analytical Solution for Beam on Elastic Foundation with Different Tension and Compression Modulus

On the basis of the theory of different modulus, the closed-form analytical solution for beams on elastic foundations with different modulus has been derived. A comparison is made between the results of the analytical solution and those calculated from the classic mechanic theories, in which the tension modulus are equal to the compression modulus. It is shown from the numerical results that the ratio of compressive modulus to tensile modulus will greatly affect the elastic characteristic values,internal forces and flexibilities. The present theory satisfies the mechanical behavior of materials. The amount of materials can be economized through rational design by using the elastic theory of different modulus.     

Influences on Engineering Properties of AS Firming Agent Modified Soil by Freeze-thaw Cycles

To study the freeze-thaw durability of Aught-Set(AS) firming agent modified soil, a series of triaxial tests were conducted. The mutual relationships between stress-strain relationship, static strength, dynamic modulus and critical dynamic stress of AS firming agent modified soil and curing time, freeze-thaw cycles, cooling temperature were deeply analyzed. The results show that the unconfined compressive strength of 7 d is 75% than that of 28 d. The stress-strain curves of AS firming-agent modified soil are strain-softening and in brittle failure shape. The static strength, critical dynamic stress and resilient modulus decrease in exponential form with the increase of freeze-thaw cycles, and after 6 cycles of freezing and thawing, the trend is stable. Under the same dynamic stress, the cumulative plastic strain of samples develop from stable state to failure because of freezing and thawing. After many times of freeze-thaw cycles, the lower the negative temperature, the little influence on the mechanic properties.     

采空区危险性的支持向量机识别

针对采空区危险性影响因素与其危险性等级之间存在着复杂非线性关系的特点,笔者提出采用支持向量机最优分类理论来识别采空区的危险性等级。研究选取岩体结构、地质构造、岩石抗压强度、弹性模量、采空区形状、矿体倾角、高跨比、空区体积等8个参数作为主要影响因素,根据支持向量机理论,提出了1-V-1的采空区分类算法,并在Matlab中编程,建立了分类预测的SVM模型。以某矿山的实测采空区为例,利用该模型进行了识别,并与BP神经网络预测结果作对比。实例研究表明,采用该方法的分类结果比神经网络更准确,与采空区调查结果一致性好,用支持向量机理论进行采空区危险性评价是可行的。     

多浓度营养盐处理对微生物胶结砂土均匀性与强度的影响

采用二次注入菌液方式，制备不同浓度营养盐处理的MICP （微生物诱导碳酸钙沉淀）胶结砂样。选用巴氏芽孢杆菌作为固化细菌，采用单一浓度（0.5、1.0 mol/L）和多浓度相结合（前期采用0.5 mol/L，后期采用1.0 mol/L）的处理方式注射营养盐（尿素/氯化钙混合液），研究多浓度营养盐结合处理方式对微生物固化砂土强度及均匀性的影响。基于试验测试分析了固化砂土试样不同区间段的强度、弹性模量以及碳酸钙含量。试验结果表明，多浓度营养盐处理方式对固化砂土试样的强度及碳酸钙含量有明显影响；多浓度营养盐结合处理方式能够保证试样有较好的均匀性条件下获得较高强度及弹性模量。基于多浓度营养盐处理方式，探讨分析了影响试样强度和均匀性的基本因素。     

Experiments on heat loss characteristics in a fully opened cylindrical cavity receiver

The climate has a great impact on highway bridge rubber bearings than on building rubber bearings. In order to study the change of the mechanical properties during the life of the plain chloroprene rubber bearings of highway bridge under freeze-thaw cycle condition, the plain chloroprene rubber bearings were processed 25, 50, 75, 100 times by freeze-thaw cycle in the standard freeze-thaw chamber, then the axial compression tests were carried. The changes of the performance indicators in the bearing capacity , the ultimate compressive strength, vertical stiffness, elastic modulus under different freeze-thaw cycles were analyzed comparatively. The results show that the plain chloroprene rubber bearings are more prone to brittle failure after the freeze-thaw cycle, and the failure phenomena of steel plate exposing or cracks is more serious than the phenomena of the standard specimen. With the increase of the number of freeze-thaw cycle, the ultimate bearing capacity, ultimate compressive strength and compressive elastic modulus of the plain chloroprene rubber bearings decrease. The attenuation formula and decay curve in 50 years of ultimate compressive strength and elastic modulus of compression are analyzed by least square method, the trends of change are both in line with the exponential function. The mechanical properties of plain chloroprene rubber bearings of highway bridge significantly decreased under freeze-thaw cycle condition. therefore, the temperature ranges of plain chloroprene rubber bearings of highway bridge should be strictly controlled, and some suggestions, such as increasing its minimum applicable temperature, usng the natural rubber bearings as much as possible in cold regions, have been given.     

The Study of the Shear Elastieity Experiment on Rat''s Aorta

It deseribes the shear elasticity of the rat's aorta and the shear modulus of therat's aorta was determined by the testin g device in d ifferent conditions. The relationship of the dif-ferent inner pressu re of vessel and the shear modulushas been determined.A nd the effect of(NA)on the shear modulus was also dealt with .Some cuvveqL wete obtained too.     

建筑垃圾细料生产流动化回填材料的性能

以灰砂比0.03、0.05和0.08,粉砂比0、0.05、0.1、0.15和0.2为设计参数,对建筑垃圾回填材料进行设计。通过试验对回填材料的流动性(流动度、泌水率)、无侧限抗压强度以及应力应变曲线、本构关系模型和弹性模量等进行研究。研究结果表明:回填材料的流动度受水固比影响较大,两者接近线性关系;流动度在200~250 mm范围,泌水率在4%~8%之间;回填材料抗压强度与灰砂比和水固比之间存在很好的幂指数关系;回填材料应力应变曲线形状与普通混凝土的相似,在此基础上提出回填材料的本构关系模型;回填材料无侧限抗压强度与弹性模量之间存在很好的指数关系。     

Relationship Between Dynamic and Static Value of Elastic Modulus in Rock

Taking the deposited-layer rock and compacted-layer rock as study target,by elastic wave experiment and uniaxial compression experiment,the physics mechanics parameters and acoustics parameters of these rock are worked out; Based on it, by the correlativity is established between dynamic and static value of elastic modulus in rock of different lithology taking nonlinear fitting,it offers reference for the study of the drill and measuring well in the exploitation of oil. Influenced by the integrality and weathering breakage degree of rock,the biggish different is existed between dynamic elastic modulus gained by dynamical method and static elastic modulus obtained by static method,and the relationship between dynamic and static value of elastic modulus is approximatively expressed as a relationship of quadratic polynomial function.     

冻融损伤对再生混凝土耐久性及与钢筋粘结性能分析

制作掺入引气剂和未掺入引气剂的100%粗骨料取代率的再生混凝土RC1和RC2两组试件以及掺入引气剂和未掺入引气剂的普通混凝土NC1和NC2两组试件,并分别对经过不同次数冻融循环试件的抗压强度、质量损失率、动弹性模量损失率进行研究。结果表明,冻融后各组试件的抗压强度、质量损失率及动弹性模量损失率均降低,对于添加引气剂的NC1和RC1两组试件损失较小,其中RC1组试件在200次冻融后抗压强度损失接近40%,质量损失率达0.5%,动弹性模量损失率38.5%。100%取代率并加入引气剂的ZRC组试件冻融后进行中心拨出实验,发生劈裂破坏和钢筋拔出破坏2种形式。再生粗骨料混凝土与钢筋的极限粘结应力均随冻融次数的增加而降低,200次冻融后极限粘结应力下降33.5,荷载滑移曲线既有上升段也有下降段。     

A THEORETICAL BASIS OF EQUATION OF CORRELATION BETWEEN STRENGTH AND ELASTIC MODULUS OF CONCRETE

The equation of correlation between compressive strength and elastic modulus of concrete is derived on the basis of modified Burger's model. The result shows that the derived equation is similar to the empirical equation of correlation between compressive strength and elastic moulus of concrete. So this empirical equation is confirmed by rheology theory of concrete.     

Analysis of Inverted Asphalt Pavement Structure Based on Cross -Anisotropy

Based on the established cross-anisotropic layered elastic theory,the effect of inverted asphalt pavement structure by granular cross-anisotropy is analyzed.The result shows that,with the decrease of granular horizontal elastic modulus,the pavement surface deflection and tensile strain at bottom of AC are increased,but the tensile stress at bottom of semi-rigid base and compressive strain at top of subgrade are decreased.The thickness of AC has significant effect on the pavement surface deflection,tensile strain at bottom of AC and compressive strain at top of subgrade,while the granular cross-anisotropy has little effect on the critical inverted pavement responses for the thicker AC.     

玉米堆的压缩弹塑性实验分析

利用LHT-1型粮食回弹模量测定仪对玉米堆在不同条件（预压力,水分）下的无侧向膨胀回弹模量进行了实验测定,分析了不同预压力（0、100kPa、200kPa）、不同水分（13.89%、15.12%、17.71%、18.74%）对玉米堆回弹模量的影响;弹塑性形变之比与预压力的关系以及每次加卸载时塑性形变的变化规律。实验结果表明：同一水分下,玉米堆的回弹模量随着预压力的增大而增大;同一预压力下,随着水分增大,玉米堆的回弹模量减小;第五圈的弹塑性形变之比随预压力的增大而减小;每次加卸载后塑性形变随加载次数的增加而减小。     

ON STUDY DIGGED FIELD MOVEMENT''S LAW BY EXPERIMENTAL METHOD OF LASER HOLOGRAPHIC MOIRE INTERFERMETRY

The high-precision displacement measuring technology of optic-measuring mechanics is, for the first time,successfully applied on the similar model of the model land-layer with a new-type variable modulus of elasticity. The angle of movement and the distributed displacement of upper and lower rock-layers are measured. The technology is a combination of laser's technology and the modern chemical sticker-it is called the sticking moire interferometry. Compared with the measured values, the result is very satisfactory.     

页岩烧结保温砌块砌体基本力学性能试验研究

通过对页岩烧结保温砌块砌体轴心抗压、沿通缝抗剪、剪压复合抗剪性能试验研究,分析其破坏特征和破坏机理。试验结果表明:页岩烧结保温砌块砌体受压破坏时,在竖向灰缝附近形成主裂缝,接近极限荷载时砌体出现表皮剥落现象;沿通缝抗剪破坏模式主要为单剪破坏,脆性明显;剪压破坏有剪磨、剪压和斜压3种类型;实测轴心抗压强度平均值高于规范值,沿通缝抗剪强度、复合抗剪强度平均值低于计算值,并分别给出砌体轴心抗压强度平均值、抗剪、剪压复合受力抗剪强度平均值建议公式;剪压复合抗剪强度随着压应力的增大而增大;建立了页岩烧结保温砌块砌体受压应力应变关系表达式;给出该类砌块的弹性模量和泊松比的建议值。     

稻谷籽粒压缩特性的实验研究

研究了含水率对稻谷籽粒压缩特性的影响,通过Brookfield质构仪对不同含水率的稻谷籽粒(含水率10.63%、12.25%、13.71%、15.18%、16.53%w.b)在Z轴(短轴)上的压缩特性进行测定,得出含水率对稻谷压缩特性的影响规律。实验结果表明:随着压缩形变的增加,稻谷籽粒受到的压力逐渐增加,当到达破裂点时达到最大值,随之急剧减小。随着含水率的增加,稻谷籽粒的压缩最大破坏力、最大破坏能、表观接触弹性模量逐渐减小,压缩最大破坏应变逐渐增加。     

Cementation Effect with Cement during Cold In Place Recycling System of Asphalt Pavement

Different kinds of structures of RAP and different contents of cement were prepared. By means of standard compaction test, unconfined compressive strength, water stability, modulus and SEM test, the cementation effect with cement was studied. It was shown that the maximum dry density of RAP mixture rose from 1.91g/cm3 to 2.00g/cm3 with the increase of cement content when A/S was 0.4. The maximum dry density of RAP mixture would rise when adding more asphalt. The unconfined compressive strength rose from 1.48MPa to 2.63 MPa and then down to 2.28MPa when cement content was 6%. The best property could be got when A/S was 0.4 and the cement content was 6% with 9.5% water. The compressive strength of RAP mixture declined after it was cured in water for 24 h, but it had the same tendency with those of which had not been maintained in water. And it is also found that RAP does not obtain better stabilities in high temperature with modular test. From SEM test, it is shown that ettringite and C S H interlace and form the netted structure, and the aggregate would be enwrapped to increase the strength.     

THE EFFECT OF THE BOND STRENGTH BETWEEN LAYERS ON COMPRESSIVE MECHANICAL PROPERTIES OF THE COMPOSITE ROCK

In this paper, on the basis of the compressive tests of composte rock, the different kinds of mechanical properties of composite rock under different bond states are discussed. Authers found that all mechanical properties of composite rock relate to the bond strength between layers and are dilferent when the layers'' bond strength is changed. With increasing the bond strength between layers of the composite rock, the limiting strength, elastic modulus, and breaking energy increase, and this phenomenon is to be stability gradually when they reach some volue, with increasing the layers'' bond strength, the poson ratio reduces.     

Mechanical Properties of Marble at High Temperature

为进一步优化超声波提取胡萝卜中β-胡萝卜紊的工艺条件,在超声功率、超声时间、提取温度、物料粒度、料液比及提取次数6个单因素试验结果的基础上,采用二水平部分因子析因设计（2—level fractional factorial design）法,筛选出了影响β-胡萝卜素提取的主要因素为提取时间（p=0．0145）、温度（p=0．0189）、料液比（p=0．0180）和提取次数（p=0．0114）。     

Procedure and General Features of Testing Breakage Resistance of Seedcoat in Euphorbia lathyris L.

The breakage resistance of the seedcoat of Euphorbia lathyris was measured in terms of compressive force and deformation. Using an Instron Universal Testing Machine, seeds of genetically divergent descent were tested at a moisture content comparable to that at harvesting time in the field.
In comparison to other crop species breakage resistance of caper spurge is characterized by low values of force and medium ones for deformation. In connection with a likewise weakly expressed degree of elasticity the large portion of damaged seeds observed during mechanical harvesting becomes understandable. Regarding the descent of seed samples the eventual implication of an unsufficient variation of the character in question is becoming evident.     

Quasi -static Mechanical Properties of SFRC under Uni -axial Compression

Using WAW-2000 a multifunction servo-controlled testing machine,uniaxial quasi-static compression experiments for the steel fiber reinforced concrete(SFRC) were conducted with three strain rates.The volume fraction(V_f)of SFRC ranged from 0% to 3%,and the matrix was C50 concrete.The whole stress-strain curves of matrix and SFRC were obtained,and the results showed that with the increase of V_f,the compressive strength increased slowly,while the toughness increase quickly.With the increase of the strain rate,the strength of SFRC increased,but the toughness decreased,and the more the Vf,the less decreasing of the toughness.The results also showed that the elastic modulus and Poisson's ratio of SFRC were not sensitive material parameters,and with the increase of V_f,the former raised slightly and the latter decreased a little,respectively.A well suited numerical expression of the compressive stress-strain curve applicable to SFRC was put forward.