地表下沉力学模型的建立及应用

针对采动覆岩移动的规律，由弯曲下沉带的挠曲特性，应用薄板挠曲理论，建立地表下沉的最大值力学模型，预测覆岩离层未注浆和注浆条件下地表的下沉值。     

二种岩石断裂韧度试样测试的稳定性分析

本文分析了 ISRM 采纳的两种具有人字形切槽的试样在测试过程中裂纹扩展的稳定性问题,计算了它们在不同加载条件和试验机刚度时各自的稳定性因子;指出对岩石等一类脆性材料,加载方式和试验机刚度对测试的稳定性有很大的影响;说明了这两种试样在稳定性方面的差异,并指出它们在稳定性上明显地优于普通直裂纹试样.     

Relation Between Non-Steady Supply Pressure and Flux for a Double Packer Conductivity Meter: An Approximate Analytical Solution

Measurement of the hydraulic coefficients of soil or rock is carried out with the aid of double packer conductivity meters in wells or boreholes. The evaluation of tests is based on the theory of creeping flow through a porous medium. The theory leads to a non-steady cylindrically and axially symmetric heat conduction problem in an infinity domain outside a circular hole with mixed boundary conditions. With the aid of a simple but efficient approximation, which describes the singularity of the boundary value, two of the three integrations in the solution can be evaluated in closed form. The analysis shows that the problem can be reduced to a simple Volterra integral equation, which is easily solved with numerical means. The solution is characterized by one single parameter, namely the aspect ratio of the cylindrical inner cavity.     

损伤围岩中爆炸应力波动的数值模拟

应用有限元方法分析了硐室损伤围岩中爆炸应力波的传播和应力分布特征，通过引入JHC本构模型和岩石损伤变量D探讨了应力波作用下岩体的损伤演化模式。研究表明:围岩初始损伤对后续爆炸应力波的波动性质、作用范围和围岩应力分布具有不同程度的影响。当初始损伤超过某临界值后会显著地影响应力波的波动范围和围岩应力分布；在一定爆炸当量下，爆炸应力存在一个有效作用范围Lp，该范围塑性区以内，爆炸应力对岩体的损伤随围岩初始损伤增大而增大；有效作用范围Lp以外，围岩初始残余非弹性变形积累和单元残余拉应力可以平衡爆炸应力波动产生的损伤叠加效应，耗散了爆炸应力作用和波动能量。分析了产生在这种现象的原因。给出了有效作用范围Lp与围岩初始等效应力p之间的经验关系。     

动能弹侵彻素混凝土板的数值模拟

用二维梁-颗粒模型BPM2D(Beam-Particle Model in Two Dimensions)模拟了刚性弹体侵彻和贯穿素混凝土板的过程．梁-颗粒模型BPM2D是在离散元法基础上,结合有限元法开发的二维数值计算模型．在模型中用三种类型梁单元形成混凝土数值试样．每种类型梁单元的力学性质均按韦布尔(Weibull)分布随机赋值以模拟混凝土细观结构的非均匀性,同时梁单元的强度随应变率不同而变化．利用此模型分析了弹体侵彻下混凝土板的破坏过程,并给出不同弹体初始速度条件下各时刻混凝土和弹体内部速度场．通过将计算结果与实验数据及LS—DYNA程序模拟结果相比较,表明梁-颗粒模型可有效应用于计算和模拟脆性材料动态破坏问题．     

裂隙岩体强度试验单点法及其前景

本文在回顾裂隙岩体强度试验的基础上，用大量原位测试数据对裂隙岩体直剪破坏机理和裂隙岩体直剪破坏的基本规律及其成因进行了深入探讨；总结出一套行之有效的试验技术；给出了裂隙岩体直剪破坏时的充分必要条件并加以量化。     

Antiplane shear fields near a crack-tip in a brittle damaged material

In this paper, a simplified brittle damage model is proposed according to the Mazarz-Lemaitre damage model for concrete. A closed-form solution for a mode III crack is obtained based on the simplified model under small scale damage conditions, which allows for discontinuities of displacement-gradient and tangential stress on the damage boundary. It is pointed out that the discontinuities of field variables near the tip region exist for the brittle damaged material induced by the softening effect of the material. The preoject supported by the National Natural Science Foundation of China     

Ⅰ-Ⅱ复合型尖V形切口脆断准则

基于最大周向应力和Seweryn-Novozhilov准则,用线弹性奇异应力场,给出Ⅰ-Ⅱ复合型尖V形切口的脆性断裂准则;并把裂纹作为切口张角为零的V形切口,这样就把V形切口问题与裂纹问题的断裂准则统一起来.为了验证该准则,本文采用有机玻璃板材加工多种V形切口试件进行了拉伸实验;同时,应用该准则对文献[16]中复合载荷下双边切口试件进行了起裂方向和临界载荷预测,并与其实验结果相比较.结果表明,本文所给出的Ⅰ-Ⅱ复合型尖V形切口脆性断裂准则与实验是相吻合的,适合于实际工程应用。     

软煤拉伸应力-应变关系的实验研究

提供一种用于测量软煤或土的抗拉强度、拉伸应力 应变关系等拉伸特性的实验装置．利用模具压制出均匀的煤环试件，对煤环内壁施加均布径向水压力使其拉伸变形和破坏．根据实验结果，提出了弹脆性拉断破坏的理论模型，并据此对煤的抗拉强度、弹性常数以及等效孔隙压力系数等进行了分析和讨论．实验数据稳定可靠，散布小，重复性好，说明所提供的实验装置和实验方法简单而有效．     

Pulse shaping techniques for testing brittle materials with a split hopkinson pressure bar

We present pulse shaping techniques to obtain compressive stress-strain data for brittle materials with the split Hopkinson pressure bar apparatus. The conventional split Hopkinson pressure bar apparatus is modified by shaping the incident pulse such that the samples are in dynamic stress equilibrium and have nearly constant strain rate over most of the test duration. A thin disk of annealed or hard C11000 copper is placed on the impact surface of the incident bar in order to shape the incident pulse. After impact by the striker bar, the copper disk deforms plastically and spreads the pulse in the incident bar. We present an analytical model and data that show a wide variety of incident strain pulses can be produced by varying the geometry of the copper disks and the length and striking velocity of the striker bar. Model predictions are in good agreement with measurements. In addition, we present data for a machineable glass ceramic material, Macor, that shows pulse shaping is required to obtain dynamic stress equilibrium and a nearly constant strain rate over most of the test duration.