综采工作面周期来压步距受回采速率影响研究

为实现不同采煤速率条件下综采工作面周期来压步距的预测,保证来压时工作面稳定,以陕北某煤矿14204工作面为工程背景,通过对工作面支架压力实时监测得出矿压显现规律,并分别采用对数函数和双曲函数对周期来压步距受推采速率的影响进行回归分析。分析结果表明,14204工作面平均来压步距为13.3 m;经过对比分析,发现双曲函数能很好的拟合推采速率对周期来压步距的影响;随回采速率的提高周期来压步距有所增加,但是由于工作面两端及中间位置的顶板所处的边界条件、地质条件等不尽相同,所以周期来压步距增加的幅度有所差异。研究成果为陕北地区综采工作面矿压显现规律的预测及控制提供了有益的实践经验。     

T型触探矩形截面探头特性研究

为了减小探头表面粗糙度的影响,提出了矩形截面T型触探探头。假定软黏土强度服从Tresca屈服条件,将矩形截面探头分解为水平无厚薄片和垂直无厚薄片,得到了矩形截面探头阻力系数近似解。在阻力特征、变形和强度方面与椭圆形截面探头进行了对比。结果表明,在探头粗糙度影响方面,以及强度和变形特征方面,矩形截面探头均优于圆形截面探头。矩形截面探头是一种适用的测试探头。     

Undrained expansion analyses of a cylindrical cavity in anisotropic sands incorporating the SANISAND model

Soils are known to be inherently anisotropic, resulting in complex responses to loading. This paper aims to develop an elastoplastic solution for the undrained expansion of a cylindrical cavity in sands adopting a non-associated and anisotropic model, SANISAND. The rigorous derivation of the stress-strain state of the soil element is provided following a standardized solving procedure. The dilatancy and crushing of the soil are invoked in the three-dimensional cavity expansion solution by adopting the critical state soil mechanics and limiting compression curve, respectively. By combining this with a governing equation that considers the undrained condition, the stress-strain state of the surrounding soil around the cavity can be determined. A subroutine is then implemented into the ABAQUS FEM simulation to verify the solution. The solutions are also validated against those based on an isotropic model, and anisotropic sand is used to investigate the effects of the initial effective mean stress, at-rest coefficient of earth pressure, and overconsolidation ratio on the stress distribution, stress path, and boundary surfaces.     

西藏芒康震群发震构造分析

2018年12月13日23时32分、39分,在西藏昌都市芒康县连续发生M4.9和M4.4地震;随后12月14日1时15分、38分、42分,该地又连续发生了3次M≥30地震,地震震中位于川滇菱形块体西北部金沙江断裂带、巴塘断裂带和藏东澜沧江断裂带所夹持的区域。基于四川及周边区域地震台网的观测资料,采用双差定位方法,对芒康震群序列进行了重新定位,并利用CAP波形反演方法,获得了5个M≥30地震的震源机制解、震源矩心深度与矩震级。根据震群序列空间展布、较大地震震源机制解和震源区附近的地质构造,初步分析认为:芒康震群序列地震展布在地表下长约16 km、宽约6 km,深度在5～20 km的区域;与震群序列空间展布方向较为一致的节面I为发震断层面,断面倾向NE,倾角约为65°,滑动角约为-34°;震源区主压应力P轴方位为近EW向,与该区域构造应力场主压应力方向一致,推测本次震群地震应是在羌塘块体物质持续E向挤入作用下,位于羌塘地块东南缘的一条NWW向次级隐伏断裂拉张运动引起的。     

水溶液中溶质的扩散同位素分馏研究

稳定同位素分析是判定水溶液中溶质的组成、来源、迁移和转化过程与规律的重要工具,在自由扩散等物理化学作用下,对溶质的同位素分馏研究是稳定同位素技术应用的重要基础.本研究介绍了溶质的扩散过程与其同位素分馏效应之间的联系,论述了研究溶质扩散过程中引入的稳定同位素分馏现象的意义,描述了水溶液中溶质扩散的不同模拟实验方法及相关研...     

两步解法用于求解线阵CCD影像外方位元素

在线阵CCD影像外方位元素的求解过程中,外方位元素之间的相关性,导致法方程病态,最小二乘估计值误差较大。本文在分析以往解决方法的基础上,提出采用两步解法求解线阵CCD影像的外方位元素。该算法的实质是选择一个比单位矩阵更合适的正则化矩阵。试验结果表明该算法能有效地克服线阵CCD影像外方位元素间的相关性,定位精度较高,定向点精度在1个像素内,检查点精度在1.5个像素内。     

New approximate solution for time-fractional coupled KdV equations by generalised differential transform method

In this paper, the generalised two-dimensional differential transform method (DTM) of solving the time-fractional coupled KdV equations is proposed. The fractional derivative is described in the Caputo sense. The presented method is a numerical method based on the generalised Taylor series expansion which constructs an analytical solution in the form of a polynomial. An illustrative example shows that the generalised two-dimensional DTM is effective for the coupled equations.     

Hydrodynamics of a headland-bay beach—Nearshore current circulation

This paper is devoted to the analysis of the hydrodynamic equilibrium of a headland or semi-elliptic shaped beach. It is shown that the state of equilibrium depends not only on the in- and outgoing sediment but also on the accommodation of the sediment within the embayment. The shape and relative depth of shoals, or settling zones, also directly affect the wave and current patterns inside the bay, within which the resultant breaker line almost stops wave-induced currents at some locations, whereas the magnitude of current increases at other locations. Several numerical tests are analytically conducted in a semi-elliptic beach with two symmetrical shoals of varying relative depth where circulatory current systems are detected and analyzed. Numerical modelling for wave climate and wave-induced current estimation is also presented in order to corroborate results and provide a tool for complicated and/or physical domains. The results lead to a redefinition of the concept of equilibrium for headland-bay beaches taking into account not only the net sediment transport but also the role of the formation and disappearance of settling zones, as well as sediment interchanges between the beach and shoals.     

埕东泡沫复合驱HPAM溶液黏度影响因素及对策研究

在油田现场复合体系的注入过程中,用回注污水配制的聚合物溶液黏度逐步下降至1～5 mPa.s,影响了现场试验效果。通过研究污水水质状况、腐蚀性、现场使用的各种化学剂以及泡沫驱体系引入的各因素对聚合物溶液黏度的影响,确定了聚合物黏度下降的主要因素,即污水中含有硫化氢（负二价硫）是造成井口注聚黏度低的主要原因。分析认为,负二价硫的来源主要是由于泡沫剂在硫酸盐还原菌的作用下转化产生的。根据聚合物黏度变化规律和降解机理,开展了聚合物黏度保留措施研究,并开展了聚合物降解抑制剂和氧化脱硫技术的现场试验。现场试验结果表明,配注聚合物溶液黏度可保持在15 mPa.s以上,增黏效果明显,对于注聚驱提高注入质量和效果具有指导意义。     

固体—液体层分界面处的P、SV型面波

针对半无限弹性固体—液体层分界面处 Ｐ、 Ｓ Ｖ 型面波不同的数学表达进行了分析研究,认为在有些著作中将它们统称为瑞利波是不够严密的,指出瑞利波和斯通利波是固体—液体层分界面处 Ｐ、 Ｓ Ｖ 型面波的两种极限情况。