Archive for the ‘Geotechnical Engineering [岩土工程]’ Category

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​本文与大家分享一个稳态渗流分析的小算例。

  • 原理概述

渗流遵从达西定律,单位面积的渗透流量公式 =ki,其中q为单位面积的渗流率,k为渗透系数,i为水力坡度。

渗流基本方程:

对于稳态渗流,土壤的含水率不随时间变化,即上式的右侧为零,则渗流方程为

  • 算例分析

下面给出一个简单的2D渗流分析算例。算例取自基坑支护的一个断面,基坑侧壁设置止水帷幕,地下水可从坑底底部渗入基坑,本算例将对这一稳态渗流过程进行简单模拟。

首先给出地质剖面图如下:

对地质剖面进行简化,建立分析模型。模型水平向范围取自基坑外轮廓至外扩约5倍基坑深度,竖直向则取坑底以下约3倍基坑深度,各层岩土分界及材料属性根据勘察报告结果进行设置。

指定水头边界条件,基坑外水头高度取自地表,基坑内水头高度取自坑底,如图所示:

  • 分析结果
下图是分析得到的渗流图,从图中可以看出,渗流主要发生在基坑边缘底部,远离基坑侧壁的部位渗流较弱。由于本算例土层的渗透系数较小,因此该剖面的渗流率也较小,仅为0.3m^3/day/m。

当然,渗流行为与地质情况是息息相关的,需要具体问题具体分析。

初学渗流分析,以上算例谨作抛砖引玉,希望各位大牛不吝赐教。学习中得到了华工院 周工 的耐心指导,在此表示感谢。


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  • 资料整理 ( Comments )

感谢小伙伴 沈雪龙 的精彩分享!!!

  • 注释 ( Comments )

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分享一个小程序。  A small program to share with you.

  • 程序图标 ( Program Icon )

        

  • 程序介绍 ( Program Introduction)

To identify grain size characteristics of soils, grain size distribution curve is developed. First, sieve analysis is conducted. A variety of sieves with different openings are stacked, with the largest opening sieve on the top and smaller on the lower sections. When a relatively large percent passing through the sieve with 0.075mm opening (e.g., more than 10% as a guideline) is obtained from the sieve analysis, a hydrometer analysis is conducted.

This program process the raw data from sieve analysis and hydrometer analysis to get the  grain size distribution curve and other parameters like D10, D30, D50, D60, Cu and Cc.

D10: effective grain size, the diameter of the soil particles for which 10% of the particles are finer.

D30: the diameter of the soil particles for which 30% of the particles are finer.

D50: mean grain size, the diameter of the soil particles for which 50% of the particles are finer.

D60: the diameter of the soil particles for which 60% of the particles are finer.

Cu: coefficient of uniformity, defined as  Cu = D60/D10.

Cc: coefficient of curvature (other terms used are the coefficient of gradation and the coefficient of concavity) defined as Cc = D30*D30/ D60/ D10 .

The coefficient of uniformity and the coefficient of gradation affect the soil packing arrangement.

  • 程序界面 ( Program Interface )

  • 例子   ( Example )

Import raw data from excel

Check Results


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  ( 如果您发现有错误,欢迎批评指正。邮箱:jidong_cui@163.com . 如果您喜欢这篇博文,请在上面给我 点个赞 吧! :-)   :-)   

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