A new formulation of garnet–clinopyroxene geothermometer based on accumulation and statistical analysis of a large experimental data set     

D. NAKAMURA 《Journal of Metamorphic Geology》2009,27(7):495-508

Published experimental data including garnet and clinopyroxene as run products were used to develop a new formulation of the garnet–clinopyroxene geothermometer based on 333 garnet–clinopyroxene pairs. Only experiments with graphite capsules were selected because of difficulty in estimating the Fe³⁺ content of clinopyroxene. For the calibration, a published subregular‐solution model was adopted to express the non‐ideality of garnet. The magnitude of the Fe–Mg excess interaction parameter for clinopyroxene (W_FeMg^Cpx), and differences in enthalpy and entropy of the Fe–Mg exchange reaction were regressed from the accumulated experimental data set. As a result, a markedly negative value was obtained for the Fe–Mg excess interaction parameter of clinopyroxene (W_FeMg^Cpx = ? 3843 J mol^?1). The pressure correction is simply treated as linear, and the difference in volume of the Fe–Mg exchange reaction was calculated from a published thermodynamic data set and fixed to be ?120.72 (J kbar^?1 mol^?1). The regressed and obtained thermometer formulation is as follows: where T = temperature, P = pressure (kbar), A = 0.5 X_grs (X_prp ? X_alm ? X_sps), B = 0.5 X_grs (X_prp ? X_alm + X_sps), C = 0.5 (X_grs + X_sps) (X_prp ? X_alm), X_prp = Mg/(Fe²⁺ + Mn + Mg + Ca)^Grt, X_alm = Fe/(Fe²⁺ + Mn + Mg + Ca)^Grt, X_sps = Mn/(Fe²⁺ + Mn + Mg + Ca)^Grt, X_grs = Ca/(Fe²⁺ + Mn + Mg + Ca)^Grt, X_Mg^Cpx = Mg/(Al + Fe^total + Mg)^Cpx, X_Fe^Cpx = Fe²⁺/(Al + Fe^total + Mg)^Cpx, K_D = (Fe²⁺/Mg)^Grt/(Fe²⁺/Mg)^Cpx, Grt = garnet, Cpx = clinopyroxene. A test of this new formulation to the accumulated data gave results that are concordant with the experimental temperatures over the whole range of the experimental temperatures (800–1820 °C), with a standard deviation (1 sigma) of 74 °C. Previous formulations of the thermometer are inconsistent with the accumulated data set; they underestimate temperatures by about 100 °C at >1300 °C and overestimate by 100–200 °C at <1300 °C. In addition, they tend to overestimate temperatures for high‐Ca garnet (X_grs ≈ 0.30–0.50). This new formulation has been tested against previous formulations of the thermometer by application to natural eclogites. This gave temperatures some 20–100 °C lower than previous formulations.  相似文献   

航空重力测量数据向下延拓的正则化算法及其谱分解   总被引：19，自引：3，他引：16  

王兴涛  石磐  朱非洲 《测绘学报》2004,33(1):33-38

基于Poisson积分方程,提出了以地面重力观测值作为控制并顾及外区影响的向下解析延拓数学模型,推导了向下解析延拓的谱分解式,在频域内分析了造成向下延拓结果不稳定的原因,进而给出了向下延拓的正则化算法,并讨论了向下延拓中的地形影响.通过对我国首次航空重力测量试验数据的处理表明,提出的方法可获得稳定、精确的向下延拓结果.  相似文献   

井中震电效应的模拟实验研究Ⅰ:井液部分   总被引：2，自引：2，他引：0  

韩学辉  何亿成  楚泽涵  袁兆羽 《地球物理学进展》2004,19(2):399-403

在总结前人对震电效应理论和实验研究现状的基础上,指出了井中震电勘探的特殊性．利用自行设计的实验系统,实验考察了直流电场对井液声学性质的影响,并对实验现象做了机理探讨．发现：当使用小功率直流电源(32V,3A)对NaCl溶液(20000mg／L)施以直流电场时,与电流强度和作用时间有关的电解导致了溶液物理化学组分的变化,当OH^-取代Cl^-时,可以使溶液的声速和幅度增大,但同时出现的气体(H2、Cl2),特别是H2导致了“气泡幕”的发生,对声波能量(幅度)的影响是决定性的,实验结果和机理分析有助于丰富对井中震电勘探实验现象的认识．  相似文献   

微生物矿化作用改善岩土材料性能的影响因素   总被引：1，自引：0，他引：1  

尹黎阳  唐朝生  谢约翰  吕超  蒋宁俊  施斌 《岩土力学》2019,40(7):2525-2546

基于微生物诱导碳酸钙沉淀作用（MICP）的土体改性技术近年来在岩土工程领域引起了人们的广泛关注。该技术在改善岩土材料的强度、刚度、抗液化、抗侵蚀及抗渗透性等性能的同时,还能维持土体良好的透气性和透水性,改善植物的生长环境。由于微生物矿化作用涉及一系列生物化学和离子化学反应,固化过程中的反应步骤较多,因此,MICP固化效果受许多因素的制约与影响。基于大量文献资料,系统总结了细菌种类、菌液浓度、温度、pH值、胶结液配比及土的性质等关键因素对微生物改善岩土材料性能的影响,讨论了这些影响因素的优化方式和未来的研究方向,主要得到了以下几点结论：菌种类型、菌液浓度、温度、pH、胶结液性质会从微观上影响碳酸钙的晶体类型、形貌和尺寸,进而在宏观层面影响岩土体的胶结效果;菌液浓度尽可能高、温度在20～40℃间、pH值在7.0～9.5左右、胶结液浓度在1 mol/L以内的因素条件对微生物加固岩土体具有较好的效果。上述范围内的低温、较高的pH值、低浓度胶结液有助于提高土体的抗渗性,而高温、较低的pH值以及中高浓度胶结液有助于提高土体的强度;MICP加固土体的有效粒径范围为10～1 000 ?m,相对密度越大、级配越好则加固效果越好。分步灌浆法、多浓度相灌注法及电渗灌浆法有助于提高土体固化均匀性,0.042 (mol/L)/h以下的注浆速度有利于提高胶结液利用率,砂土试样的灌浆压力一般在10～30 kPa之间,粉黏土试样的灌浆压力不宜超过110 kPa,过高的灌浆压力会破坏土体结构,降低固化效果。  相似文献   

Consolidation around a point heat source (correction and verification)     

Aqeel Afzal Chaudhry  Jörg Buchwald  Olaf Kolditz  Thomas Nagel 《国际地质力学数值与分析法杂志》2019,43(18):2743-2751

  相似文献   

再论岩质高边坡稳定性分析方法     

李宁  郭双枫  姚显春 《岩土力学》2018,39(2):397-406

岩质高边坡稳定性分析是岩土工程中经典的研究课题,其假定不同,分析方法就不同。从现有稳定性分析方法中存在的问题入手,指出其存在的优劣性,在刚体极限平衡和有限元等传统边坡稳定性分析方法的基础上,提出了用有限单元法直接求解边坡稳定性。该方法的思路是用潜在滑动面上在开挖、支护完成后尚未发生滑动的所有滑面单元模拟边坡在各工况下的真实应力场和变形场,根据这个真实应力场直接计算边坡安全系数。结合现场即时监测手段和计算机仿真技术可逐步模拟边坡在分步开挖期间的稳定性。算例分析表明,该方法完善了刚体极限平衡法的不足,克服了强度折减法强度参数c、?值折减比例的难题,弥补了超载法力学方向不明确的缺陷。计算所得的边坡安全系数和稳定状态与工程实际相当接近,表明提出的方法是可靠有效的新方法,为复杂岩质边坡稳定性分析提供了新的思路和途径。  相似文献   

一种基于里程参数的道路平面几何解析模型   总被引：1，自引：0，他引：1  

陶璐  朱敦尧  王军德  张攀 《测绘通报》2017,(3):52

随着主动安全技术、自动驾驶技术的发展,高精度导航地图得到越来越多的运用。本文提出了一种面向高精度导航地图的、基于里程参数的道路平面几何解析模型。通过动态地构造点集上的正交多项式系和约束最小二乘法,根据拟合最大误差动态地计算道路的几何描述参数。使用该模型进行了120 km高速道路高精度地图数据生产,以三段典型道路为实例进行试验,表明该方法能对道路几何进行准确的描述,保证道路几何的连续与光滑,同时最大限度地减少数据冗余。该模型对高精度地图道路几何描述具有一定优势。  相似文献   

赣南稀土精矿粉配制的稀土溶液反射波谱特征研究     

代晶晶  王登红  陈郑辉 《地球学报》2017,38(4):523-528

赣南离子吸附型稀土矿是我国重要的稀土资源,本文运用美国ASD FieldSpec-3便携式地物波谱仪,对赣南寻乌稀土矿区稀土精矿粉配置的25个稀土溶液样品进行波谱测试,获取了不同稀土含量的波谱特征,结果表明溶解在水体中的稀土元素在可见光-近红外574 nm、790 nm、736 nm、520 nm、861 nm、443 nm等波段具有多个明显的稀土特征吸收谷及若干次级的稀土特征吸收谷;通过与15种稀土单元素波谱特征对比分析,可见这些吸收特征主要由一种或几种稀土单元素引起;随着稀土浓度的降低,这些吸收特征逐渐减弱甚至消失。这一研究进一步加深了对我国赣南稀土溶液波谱特征的认识,同时为赣南稀土元素的高光谱遥感研究奠定了理论基础。  相似文献   

Nonlinear dynamics and impact load in float-over installation     

《Applied Ocean Research》2017

A time-domain 3 Degrees of Freedom model is developed to investigate nonlinear dynamics and impact loads during float-over installations, which generally involve multi-body interactions between wave-induced vessel motions and nonlinear constraint components. By replacing the time-consuming convolution in calculating the retardation function, a more efficient method, i.e. state-space model, is applied to evaluate part of the radiation force. The established model, incorporating the multi-body interactions, is applied to study the nonlinear impact on Leg Mating Unit (LMU) by considering the sway, heave and roll motions of the float-over system. The structural characteristics are considered when modelling the characteristics of LMU. The dynamic behaviors of a given system is investigated in the form of bifurcation diagrams, along with impact map, amplitude spectrum and power spectral density (PSD). It is found that bifurcation phenomena, or a large angle of docking cone could dominate the installation due to the increased impact loads.  相似文献   

Numerical study of nonlinear freak wave impact underneath a fixed horizontal deck in 2-D space     

《Applied Ocean Research》2017

Freak waves are extreme and unexpected surface waves with huge wave heights that may lead to severe damage to ships and offshore structures. However, few researches have been conducted to investigate the impact underneath fixed horizontal decks caused by freak waves. To study these phenomena, a 2-D numerical wave tank is built in which nonlinear freak waves based on the Peregrine breather solution are generated. As a validation, a regular-wave-induced underneath impact is simulated and compared to the existing experimental measurements. Then the nonlinear freak-wave-induced impact is investigate with different values of deck clearance above the mean free surface. In addition, a comparative simulation of a “large” regular wave based on the 2nd-order Stokes wave theory with the same crest height and wave length of the nonlinear freak wave is carried out to reveal the unique features of the nonlinear freak-wave-induced impact. By applying a fluid–structure interaction (FSI) algorithm in which the bottom deck and front side wall are simplified as Euler beams in 2-D and discretized by the finite element method (FEM), the hydroelastic effects are considered during the impact event. The vertical force acting underneath the bottom deck, the transversal force acting on the front side wall, the structural displacements of the elastic deck and wall are analyzed and discussed respectively, from which meaningful conclusions are drawn.  相似文献