按照ISO 6892-1:2019附录G方法评定弹性模量的测量不确定度

利用方差合成规律和不确定度定义为方差的正平方根,导出拉伸试验测定的弹性模量的合成标准不确定度表示式,其可以用于评定弹性模量的合成标准不确定度.实例评定结果表明ISO 6892-1:2019附录G中式(G.4)的评定结果明显偏低,原因是式(G.4)缺失了力测量设备准确度级和延伸测量仪器准确度级所允许的误差而引起的不确定度...     

Numerical investigation of fracture behavior of tunnel by excavation loading

A rock failure process analysis model, RFPA2D code, a two-dimensional numerical code, were proposed. The code not only satisfied the global equilibrium, strain consistent and nonlinear constitutive relationship of rock and soil materials but also took into account the heterogeneous characteristics of rock materials at macroscopic and microscopically level. The failure behavior of tunnel could be simulated by this numerical model. The model could realistically simulate the fracture behavior of tunnel by excavation loading, strength limits, and post peak response for both tension and compression. As the proposed method was used to conduct the stability analysis of tunnel, the safety factor of tunnel was defined as the ratio of actual shear strength parameter to critical failure shear strength parameter. Not only the safety factor of tunnel with specific physics meaning can be obtained, but also the overall failure process and the location of failure surface may also be determined at the same time.     

Study on rock burst of fully mechanized sublevel caving mining in deep mine

The theoretical analysis, numerical simulation and field observation were used to study distribution characters of abutment pressure of fully mechanized sublevel caving face in deep mine, fully mechanized sublevel caving and pressure relief in entries along goaf to the influence of rock burst. The results show that： （1） With the increasing of mining depth, the abutment pressure zone is larger, its peak point is transferred to the front of face, the danger area occurring rock burst in the two fully mechanized sublevel caving entries is larger, and its position is far from the face; （2） There is larger failure area in the upper coal in front of the fully mechanized caving face, and strata possibly occurring rock burst transferred to the upwards or far from faces because of the main roof＇s buffer effect to the dynamic pressure burst, then possibility and strength reduced; （3） The position occurring rock burst is stress concentration zones （abutment pressure along the goaf and residual tectonic stress） and zones with geological structure; （4） Strenuous activities of roof is the inducing factor occurring rock burst.     

超声马达各向异性摩擦材料性能的试验研究

根据超声马达对摩擦材料切向和纵向性能的不同要求,采用在酚醛树脂胶中添加玻璃丝布和玻璃纤维增强的方法制备出不同弹性模量匹配的各向异性摩擦材料,并对其性能进行了测试。结果表明:当摩擦材料垂直方向与水平方向的弹性模量的比值为0.71~1.42时,摩擦材料受振动头的正压力和驱动力先增大后减小,比值为1.24时,马达的正压力和驱动力最大,驱动效果最好。     

循环荷载下北山花岗岩能量耗散与损伤特征

以高放废物地质处置库甘肃北山预选区花岗岩为研究对象,开展三轴循环加卸载试验,探究循环荷载作用下岩石耗散能、摩擦耗能、破碎耗能的演化特征,提出基于破碎耗能的岩石损伤变量.结果表明:依据耗能比曲线和应力-应变曲线演化特征,可将循环加卸载过程划分为初始压密与弹性段、裂纹稳定发育段、裂纹不稳定发育段、峰后不稳定破裂段和残余强度...     

克拉美丽气田石炭系火山岩压裂改造规律探索

准噶尔盆地克拉美丽气田石炭系火山岩储层的压裂改造是其“增储上产”和产能评价的重要手段,然而,储层发育部分连通性不佳的微细裂缝在压裂后易于形成复杂裂缝,包括转向裂缝、鱼刺状小裂缝、不同方位的多裂缝、同方位的多裂缝及纵向上的多裂缝等。为此,利用诊断复杂裂缝的近井筒效应分析技术、压裂施工过程分析技术、压后压力分析技术,进行了10井次的对比分析。结果表明：10口井压裂没有产生大的分支裂缝,但是全都产生了裂缝弯曲,其中有50%为轻微弯曲,20%为中等弯曲,30%为严重弯曲。进而得出了克拉美丽气田石炭系火山岩压裂一般不会产生较大的分支裂缝,但是总会产生不同程度的裂缝弯曲的初步认识。     

岩石压缩系数与孔隙度的关系

岩石压缩系数与孔隙度的关系问题是一直没有得到很好解决的理论问题 ,传统的经验公式示出岩石压缩系数随孔隙度的增大而减小。本文应用多孔介质力学的有关理论 ,推导出了岩石压缩系数与孔隙度之间的理论关系式。该关系式表明 :岩石的压缩系数随孔隙度的增大而增大 ;岩石压缩系数受成岩矿物硬度的影响 ,矿物硬度越大 ,岩石的压缩系数越小。上述研究成果对油藏工程研究具有重要意义。     

考虑岩层各向异性性质的井壁位移分析

井眼钻成后,由于岩石的蠕变而常发生井眼缩径,使钻具、套管和测井仪器难以下到井底,本文应用粘弱性理论,对横观各向同性岩层井眼的位移进行了分析,推导出井眼径向位移与原地应力、岩层的各向异性特性、稳定周期及钻井液密度的关系式,本文的分析和给出的计算公式对在横观各向同性岩层钻井设计和施工具有一定的指导意义。