1.1 試(shi)驗土樣(yang)準備及要求(qiu)

一(yi)般情況下(xia)，十(shi)(shi)(shi)字(zi)(zi)板(ban)(ban)(ban)剪(jian)(jian)切(qie)試驗是十(shi)(shi)(shi)字(zi)(zi)板(ban)(ban)(ban)插入到取樣(yang)(yang)管中土(tu)(tu)(tu)(tu)樣(yang)(yang)進(jin)行(xing)測(ce)試。土(tu)(tu)(tu)(tu)樣(yang)(yang)高度(du)(du)應大于6倍十(shi)(shi)(shi)字(zi)(zi)板(ban)(ban)(ban)板(ban)(ban)(ban)頭(tou)寬(kuan)度(du)(du)（6 D），十(shi)(shi)(shi)字(zi)(zi)板(ban)(ban)(ban)板(ban)(ban)(ban)頭(tou)頂端與(yu)(yu)(yu)上一(yi)深度(du)(du)的(de)土(tu)(tu)(tu)(tu)樣(yang)(yang)剪(jian)(jian)切(qie)面(mian)(mian)底(di)面(mian)(mian)距離(li)應大于2倍十(shi)(shi)(shi)字(zi)(zi)板(ban)(ban)(ban)板(ban)(ban)(ban)頭(tou)寬(kuan)度(du)(du)（2 D）。如有(you)需要，同(tong)一(yi)土(tu)(tu)(tu)(tu)樣(yang)(yang)可在同(tong)一(yi)高度(du)(du)的(de)不(bu)同(tong)位(wei)置進(jin)行(xing)平行(xing)剪(jian)(jian)切(qie)試驗測(ce)試，任意(yi)十(shi)(shi)(shi)字(zi)(zi)板(ban)(ban)(ban)剪(jian)(jian)切(qie)面(mian)(mian)與(yu)(yu)(yu)其相鄰十(shi)(shi)(shi)字(zi)(zi)板(ban)(ban)(ban)剪(jian)(jian)切(qie)面(mian)(mian)和土(tu)(tu)(tu)(tu)樣(yang)(yang)外邊緣(yuan)間的(de)距離(li)應大于1倍十(shi)(shi)(shi)字(zi)(zi)板(ban)(ban)(ban)板(ban)(ban)(ban)頭(tou)寬(kuan)度(du)(du)（1 D）。試驗前，用削土(tu)(tu)(tu)(tu)刀整(zheng)平土(tu)(tu)(tu)(tu)樣(yang)(yang)表面(mian)(mian)，并(bing)將其固定在十(shi)(shi)(shi)字(zi)(zi)板(ban)(ban)(ban)板(ban)(ban)(ban)頭(tou)正下(xia)方，依(yi)據土(tu)(tu)(tu)(tu)樣(yang)(yang)軟硬程(cheng)度(du)(du)選用相應尺寸和規格的(de)十(shi)(shi)(shi)字(zi)(zi)板(ban)(ban)(ban)板(ban)(ban)(ban)頭(tou)，并(bing)與(yu)(yu)(yu)十(shi)(shi)(shi)字(zi)(zi)板(ban)(ban)(ban)剪(jian)(jian)切(qie)儀連接。

1.2 試驗流程

試驗(yan)流程如下：

1）試驗前檢(jian)查(cha)各(ge)部件連(lian)接是否(fou)正常(chang)可靠(kao)；

2）將十(shi)字板(ban)(ban)板(ban)(ban)頭(tou)對準(zhun)土樣(yang)(yang)中心，垂直插入土樣(yang)(yang)直至十(shi)字板(ban)(ban)板(ban)(ban)頭(tou)頂端距(ju)離(li)土樣(yang)(yang)表面(mian)至少2倍十(shi)字板(ban)(ban)板(ban)(ban)頭(tou)寬度，然后靜置(zhi)2 min ~3 min；

3）將采集儀或(huo)刻度表(biao)調零或(huo)讀(du)取(qu)初讀(du)數；

4）順時(shi)針(zhen)方向以6 o~12 o/ min轉(zhuan)速旋轉(zhuan)。每轉(zhuan)1°記錄扭(niu)轉(zhuan)度和(he)(he)扭(niu)矩讀數1次，當(dang)扭(niu)矩讀數出現峰值(zhi)或穩定值(zhi)（波動(dong)不(bu)超過5 %）后，記錄扭(niu)轉(zhuan)度和(he)(he)扭(niu)矩讀數，再(zai)繼續旋轉(zhuan)測記一段時(shi)間(jian)（宜(yi)1 min左右）。扭(niu)矩峰值(zhi)或穩定值(zhi)作為(wei)原(yuan)狀土剪切破壞時(shi)的讀數；

5）在上(shang)述剪損土樣基礎上(shang)，立即(ji)進行重塑土抗剪強度的測(ce)定(ding)。將十字板板頭(tou)按順時針方(fang)向(xiang)快速(su)旋(xuan)轉6 圈后，重復上(shang)一(yi)步操作(zuo)測(ce)定(ding)重塑土抗剪強度；

6）選(xuan)取代表性樣品測試含水率(lv)，檢查破壞面的破裂情況，并記錄試驗過程中發(fa)現的情況；

7）如(ru)需測(ce)(ce)量較深處土樣的(de)抗剪強度(du)(du)，除按照本條第2~5 款規定(ding)外，還應修正軸(zhou)桿與土樣之間(jian)的(de)摩阻力影響，以減小試驗誤差。方法(fa)是將未(wei)安裝十字板(ban)(ban)板(ban)(ban)頭(tou)的(de)軸(zhou)桿插入(ru)同樣深度(du)(du)的(de)土樣中(zhong)測(ce)(ce)量扭(niu)(niu)矩(ju)，實(shi)際測(ce)(ce)量時將十字板(ban)(ban)板(ban)(ban)頭(tou)實(shi)際測(ce)(ce)試扭(niu)(niu)矩(ju)減去該扭(niu)(niu)矩(ju)即為土樣的(de)扭(niu)(niu)矩(ju)。