某建筑物的基础图如下,图中轴线为墙中心线，墙体为普通黏土实心一砖墙,室外地面标高为-0.3m ，求该基础人工挖土的工程量（ Ⅲ类干土）
解： h =2.5 0.1 – 0.3 = 2.3 m >1.5 m 放坡
k = 0.33 c = 300 mm
(1) 基坑挖土计算
J—1 开挖断面上底宽 b = a 2c 2kh
= (0.8*2 0.1*2) 2 * 0.3 2* 0.33 *2.3 = 3.918m
开挖断面下底宽 B= a 2c
=1.8 2*0.3 = 2.4 m
J—1 基坑挖土V = h/6[AB (A a)(B b) ab]
=h/6
= 2.3/6[3.9182 (3.918 2.4)2 2.42]
= 23.394 m3
J—2 开挖断面上底宽 b = a 2c 2kh
=(1.05*2 0.1*2) 2*0.33*2.3 = 4.418 m
开挖断面下底宽 B= a 2c = 2.3 2*0.3 =2.9 m
J—2 基坑挖土V = h/6[AB (A a)(B b) ab]
=h/6
= 2.3/6[4.4182 (4.418 2.9)2 2.92]
= 31.235 m3
基坑挖土V = 4V 2V =4*23.394 2*31.235
= 156.05 m3
(2) 沟槽挖土计算
开挖断面上底宽 b = a 2c 2kh
=0.7 2*0.3 2*0.33*(2.5 – 0.3)=2.752m
开挖断面下底宽 B= a 2c = 0.7 2*0.3 =1.3 m
沟槽长度 = 2*(8 – 2.2 –2.7) 2*(6 – 2*1.18) (6-2*1.43)
= 16.62 m
沟槽挖土V = (2.752 1.3)*2.2* ? * 16.62 = 74.08 m3
答:该基础挖基坑土156.05 m3 ; 挖沟槽土74.08 m3 .
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