The smooth joint contact model has been used extensively to simulate the shear behaviour of joints in the numerical simulations with particle flow code. Results from existing studies have revealed that this model suffers from the particle interlocking problem taking place at the shear displacement greater than the minimum particle diameter. To solve this problem, the shear box genesis approach was proposed, by which particles in the upper and lower halves of a joint are generated separately, and the intended joint plane will be added as a common boundary. However, the shear box genesis approach is not a satisfactory solution to the interlocking problem yet. Three problems are usually encountered in practice: first, particles are still likely to move across the intended joint plane and cause the interlocking; second, the shear box genesis approach inevitably causes the periodic change in the contact number along the intended joint plane; third, it is difficult to incorporate the nonlinear closure behaviour of joints. Therefore, this paper aims to solve the shortcomings, and to apply the improvements to the simulation of joint shear behaviour. The interlocking problem was successfully solved by introducing the joint side checking method, and specifying the value of maximum allowed closure. The periodic stress fluctuation during shearing was eliminated by the non-unified ball generation method. The nonlinear closure behaviour of joints was captured by embedding the Barton–Bandis model. To verify the applicability of the improvements to rough joints, a series of numerical and experimental direct shear tests of rough joints were conducted. In general, good agreements were achieved between the numerical modelling results and laboratory measurements. This improved shear box genesis approach enhances the ability of the smooth joint contact model to simulate the shear behaviour of joints, and also has the ability to track the damage evolution during the joint shearing process.

中文翻译：

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在粒子流代码（2D）中使用改进的剪切盒生成方法对节点的剪切行为进行建模及其验证

在带有粒子流代码的数值模拟中，光滑的接头接触模型已被广泛用于模拟接头的剪切行为。现有研究的结果表明，该模型在剪切位移大于最小粒径时会发生颗粒互锁问题。为了解决这个问题，提出了剪切盒生成方法，通过这种方法，分别生成关节上半部分和下半部分的粒子，并将预期的关节平面添加为公共边界。然而，剪切箱发生方法还不能令人满意地解决联锁问题。在实践中通常会遇到三个问题：首先，粒子仍可能在预定的接合面上移动并引起互锁。第二，剪力箱成因法不可避免地导致接触数沿预期的接合面周期性变化；第三，很难纳入节点的非线性闭合行为。因此，本文旨在解决该缺陷，并将改进应用于接头剪切行为的仿真。通过引入接头侧检查方法并指定最大允许闭合值，成功解决了互锁问题。通过非统一球产生方法消除了剪切过程中的周期性应力波动。通过嵌入Barton-Bandis模型来捕获关节的非线性闭合行为。为了验证改进对粗节的适用性，进行了一系列数值和实验的粗节直接剪切试验。一般来说，在数值模拟结果和实验室测量结果之间达成了良好的协议。这种改进的剪切盒生成方法增强了光滑的关节接触模型模拟关节剪切行为的能力，并且还具有跟踪关节剪切过程中损伤演变的能力。