Stokes和Hotine积分离散求和的快速算法

提出了一种用于Stokes积分和Hotine积分直接离散求和的快速算法。该算法将积分核表达为计算点纬度、流动点纬度和两点间经度差的函数,充分利用核函数的对称性,相同纬度的所有计算点只需计算一组核函数,计算次数远少于普通离散求和。基于EGM2008地球重力位模型的模拟实验表明,快速算法的计算效率远高于普通算法,有效解决了离散求和计算速度太慢的数值问题,且保留了球面积分的特性,可取代一维FFT用于计算Stokes积分和Hotine积分。     

FLAC有限差分在地基沉降计算中的应用

介绍了有限差分法计算软件FLAC以及该软件在计算地基沉降时的步骤。通过对一个实际工程的计算对比，发现FLAC和分层总和法这两种方法计算得到的地基沉降量结果之间的误差仅为1．2mm，满足地基设计的要求，且FLAC有限差分法计算地基沉降量具有较好的准确性、直观性和简便性。     

上海地区勘察阶段估算高层住宅沉降量的实用方法

勘察设计阶段估算基础沉降量时通常采用等代实体基础的分层总和法,但由此计算出的最终沉降量一般与实测值差别较大。这一差别就会导致勘察和设计工作过于保守,造成不必要的浪费。实际工作中学术界对此也做了大量的工作,分析了产生误差的原因,也提出了使计算结果更为准确的计算方法。但鉴于勘察阶段对沉降量计算的要求,以及等代实体基础的分层总和法积累多年的经验,本文考虑在不改变计算方法的前提下,提出一个实用简便的方法计算沉降:对经验附加应力赋予一个调整系数,使计算所得的最终沉降量更接近实测值。     

黄河中游区水,沙变化趋势及其预测

本文用灰色系统分析方法对黄河中游区干、支流主要测站水、沙资料进行研究、评估,阐明了水、沙多年变化趋势,论证了水、沙多年变化的原因,并对几个测站试作水、沙长期预测。     

Application of Gaussian Beam Summation Migration in Reflected In-seam Wave Imaging

The geological conditions for coal mining in China are complex, with various structural issues such as faults and collapsed columns seriously compromising the safety of coal mine production. In-seam wave exploration is an effective technique for acquiring detailed information on geological structures in coal seam working faces. However, the existing reflected in-seam wave imaging technique can no longer meet the exploration precision requirements, making it imperative to develop a new reflected in-seam wave imaging technique. This study applies the Gaussian beam summation (GBS) migration method to imaging coal seams'' reflected in-seam wave data. Firstly, with regard to the characteristics of the reflected in-seam wave data, methods such as wavefield removal and enveloped superposition are employed for the corresponding wavefield separation, wave train compression and other processing of reflected in-seam waves. Thereafter, imaging is performed using the GBS migration technique. The feasibility and effectiveness of the proposed method for reflected in-seam wave imaging are validated by conducting GBS migration tests on 3D coal-seam fault models with different dip angles and throws. By applying the method to reflected in-seam wave data for an actual coal seam working face, accurate imaging of a fault structure is obtained, thereby validating its practicality.     

Crustal deformation in northern Central America

Evaluation of the seismic moment tensor for earthquakes on plate boundary is a standard procedure to determine the relative velocity of plates, which controls the seismic deformation rate predicted from the slip on a single fault. The moment tensor is also decomposed into an isotropic and a deviatoric part to discover the relationship between the average strain rate and the relative velocity between two plates. We utilize this procedure to estimate the rates of deformation in northern Central America where plate boundaries are seismically well defined. Four different tectonic environments are considered for modelling of the plate motions. The deformation rates obtained here compare well with those predicted from the plate motions models and are in good agreement with actual observations. Deformation rates on faults are increasingly being used to estimate earthquake recurrence from information on fault slip rate and more on how we can incorporate our current understanding into seismic hazard analyses.     

真空-堆载联合预压的地基沉降简化计算方法

研究了负压作用下的地基沉降简化计算方法，负压作用下的地基沉降计算应考虑其受力特点的影响，实际工程观测表明，现有规范对真空预压地基的沉降估算修正系数过大。通过理论推导，建立了真空预压及真空-堆载联合预压作用下地基沉降修正系数公式。分析结果表明，一般真空预压工程修正系数ms取值范围可在0.55～1.20之间，真空-堆载联合预压的分层总和法计算修正系数可取0.70～1.30。     

5400阶次勒让德函数的递推计算方法

超高阶球谐重力场模型由超高阶次勒让德函数构成。即使采用压缩因子递推计算超高阶(如大于3600阶)勒让德函数,在两极附近仍然会出现溢出(上溢或下溢)而导致计算失败。基于对递推公式的分析,利用改进的压缩因子修正递推算法,可以得到直到5400阶次高精度"压缩勒让德函数",且仍可用Horner技术求和。