岩土力学
巖土力學
암토역학
ROCK AND SOIL MECHANICS
2014年
2期
339-345
,共7页
模型试验%高能量冲击%淤泥%孔隙水压力%特征规律
模型試驗%高能量遲擊%淤泥%孔隙水壓力%特徵規律
모형시험%고능량충격%어니%공극수압력%특정규률
model experiment%high energy impact%muck%pore water pressure%variation law
以往动力排水固结室内试验,通常冲击能量不够,很难激发软土某些工程响应,对应加固机制难以发现。通过可提供高冲击能的多向高能高速电磁力冲击智能控制试验系统,针对淤泥类超软土进行静动力排水固结模型试验,获得了淤泥孔压等响应特征:夯击瞬间(6 ms)上部孔压增长及下降时间非常短,且其重复性好;初始两遍夯击结束后中部孔压变化呈双峰型,其时间间隔随着夯击遍数增加而逐渐变大,最后不复存在;每遍夯击瞬时中部土压均出现急剧增长与快速减小,增长幅度随夯击遍数增加呈减小趋势,但每遍夯完后数天内土压值均大于夯前值;每遍夯击孔压消散后最终值都小于初始孔压,说明在一定的排水条件下,淤泥这类超软土地基确实可夯击;夯击后残余应力作用机制存在,且其对沉降起主要作用,而一定静力荷载的这种机制不明显;排水板插设扰动效应不可忽视,但该扰动效应随软土埋深增大而减少。
以往動力排水固結室內試驗,通常遲擊能量不夠,很難激髮軟土某些工程響應,對應加固機製難以髮現。通過可提供高遲擊能的多嚮高能高速電磁力遲擊智能控製試驗繫統,針對淤泥類超軟土進行靜動力排水固結模型試驗,穫得瞭淤泥孔壓等響應特徵:夯擊瞬間(6 ms)上部孔壓增長及下降時間非常短,且其重複性好;初始兩遍夯擊結束後中部孔壓變化呈雙峰型,其時間間隔隨著夯擊遍數增加而逐漸變大,最後不複存在;每遍夯擊瞬時中部土壓均齣現急劇增長與快速減小,增長幅度隨夯擊遍數增加呈減小趨勢,但每遍夯完後數天內土壓值均大于夯前值;每遍夯擊孔壓消散後最終值都小于初始孔壓,說明在一定的排水條件下,淤泥這類超軟土地基確實可夯擊;夯擊後殘餘應力作用機製存在,且其對沉降起主要作用,而一定靜力荷載的這種機製不明顯;排水闆插設擾動效應不可忽視,但該擾動效應隨軟土埋深增大而減少。
이왕동력배수고결실내시험,통상충격능량불구,흔난격발연토모사공정향응,대응가고궤제난이발현。통과가제공고충격능적다향고능고속전자력충격지능공제시험계통,침대어니류초연토진행정동력배수고결모형시험,획득료어니공압등향응특정:항격순간(6 ms)상부공압증장급하강시간비상단,차기중복성호;초시량편항격결속후중부공압변화정쌍봉형,기시간간격수착항격편수증가이축점변대,최후불복존재;매편항격순시중부토압균출현급극증장여쾌속감소,증장폭도수항격편수증가정감소추세,단매편항완후수천내토압치균대우항전치;매편항격공압소산후최종치도소우초시공압,설명재일정적배수조건하,어니저류초연토지기학실가항격;항격후잔여응력작용궤제존재,차기대침강기주요작용,이일정정력하재적저충궤제불명현;배수판삽설우동효응불가홀시,단해우동효응수연토매심증대이감소。
General dynamic drainage consolidation laboratory test, as tamping impact energy is not enough, some basic mechanical responses of soft soil in the actual project are difficult to excite, and relative features of soil are difficult to find. Through the self-developed multi-directional high energy electromagnetic force impact test system which can provide high impact energy produced by electromagnetic force and therefore could simulate the tamping energy acted in practice engineering, static and dynamic drainage consolidation model test for muck, is carried out. The experimental study obtains the response characteristics of pore pressure of this ultra-soft soil as follows:the time that upper pore pressure increases sharply to the maximum, which is very short (only 6 ms) at impact instant, and after the peak it drops rapidly to a certain value;in the initial twice tamping, the curve of pore water pressure at middle deep position shows bimodal type, the time interval between the two peak increases with the increase of tamping times gradually, and finally disappeared;each tamping, instantaneous earth pressure in the middle position shows a sharp growth and rapid decrease, and growth magnitude with the increase of tamping times shows a trend of decrease, but earth pressure value after tamping several days later is still greater than the value before tamping each time;after each tamping dissipating, the final value of pore pressure is less than the initial pore pressure, which signifies that under the certain condition of drainage, such ultra-soft soil foundation can be, indeed, acted by dynamic loading; the action mechanism of residual stress produced by dynamic tamping for soil consolidation exists, and it plays a main role for settlement, but for certain static loading, corresponding mechanism is little; the disturbance effect of inserting drainage board could not be ignored, but the disturbance effect decreases with soft soil embedded depth.