【正文】 4. 結(jié)論 基于 Asaoka 觀測法的理論來源，結(jié)合對江蘇海相粘土的研究，本文發(fā)展了一種軟土路基上分期施工時路堤沉降預測的方法?？⒐ず蟮穆返坛两翟诮ǔ珊蟮?15 年里必須小于 30cm。也就是說，下一個施工期的路堤的狀況可由上一個施工期的 0? ， 1? 進行估算。 2. 分期觀測法 Asaoka 建議采取一個“觀測過程”，利用現(xiàn)場觀測的數(shù)據(jù)來估算最終沉降量和原位固結(jié)系數(shù)。 分期施工對于軟土地基上的路堤來說是一個特殊的程序。 This means that Asaoka method can be extended to obtain the construction settlement , which equals to the intercept 0? of the liner line in the space Sj Sj1, where t = 0 is set just after loading. Moreover , this immediate settlement contributes the shift distance of the parallel lines during stage construction. In fact , from the derivation of the Asaoka method , the settlement of soil layers can be expressed as and ?????? ?????????? )(51)(31)(41)(21),( 243242 FCZFCZZFTCZTCZTzt VVVV ！?。。? where T and F are two unknown function of time. With the vertical drainage boundary conditions and at the ground surface , ),( zt? =T=? (t , z=0) . If t = 0 , ),( zt? =? (t=0 , z=0) = e? = initial elastic strain. Therefore , S(t=0)=S0 gives the immediate settlement Se , which can also be estimated from the elastic method by the equation : It is clearly shown that the Asaoka method has been extended to predict the settlement of embankments with stage construction. In other words , the behavior of next stage construction can be predicted with the 0? , 1? from the last stage construction. The more the previous stages with settlement measurement , the higher the accuracy of next stage prediction. The stage observational method includes following steps : (1) Sketch observed time settlement curve . (2) Choose a time interval? t , which usually ranges from 10 to 100 days , read the settlements Sj from the curve at times t j ( = ? t j , j = 1 ,2 ,3, …). (3) Plot the settlements Sj , Sj1 in a coordinate system with axis Sj , Sj1 originated from 0. (4) Fit the plotted points by a straight line , of which corresponding slope is read as 1? . The intercept at the Sj axis gives 0? , while the point of intersection with the 45o line , gives the final consolidation settlement of the first stage. (5) From the 0? of the first stage construction to determine the undrained modulus Eu by inverse analysis (10) . (6) Determine the next stage construction settlement with the above known Eu (10) , thus resulting in the shift distance of line. (7) Assume the CV remains constant during stage construction and settlement is small pared with the thickness of soft soils , this makes the line of next stage construction parallel to the first stage with the slope 1? . (8) Predicting the final settlement of next stage construction from the intersection of the shifted line with the 45o line. (9) Estimate the Ch and CV from the value of 1? with the equation (5) or (6) . 3. Case study 3. 1 Site and project description Section A of Lianxu highway is a 31 km long high standard expressway connecting the port city Lianyugang to the national highway system of China. It was began to construction from Dec. 1999. There are 104 bridges or culverts or passways in this 31 km long section designed to connect embankments . The bottom width of the embankment is 40 m , while the height of embankment changes from 3 to 7 m. Based on the design code , the differential settlements between embankments and structures have to be controlled less than 10 cm. Post construction settlements of embankments have to be less than 30 cm during the post construction period of 15 years . It is clear that the magnitude and rates of the embankment settlements are the extremely important problem to make the project reliable and economical . 3. 2 Subsurface conditions The section A of Lianxu highway passes over the marine deposit plain. The typical subsoil profile consists of 0 to 3m think upper crust of stiff clay underlain by a to 13m thick soft clay ,which is named Jiangsu Marine clay. Blow this soft clay , lies alternating layers of stiff clay