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Figs. 12a,b show the case ofGRS-BW placed on a deformable ground with a relatively smallvalue of kv ¼ 1.3 kPa/mm. Compared to Figs. 11a,b, the walldisplacements and the shear band intensities decreased despite thegreater foundation and backfill crest settlements. This also leads to the same conclusion based on Figs. 8b and 9b for CWs, i.e., therewas a critical foundation settlement of Smax/Hj5%, induced bya subgrade reaction coefficient of kv ¼ 1.8 kPa/mm, for which theworst scenario of wall and backfill displacements occurs.4. Wall displacements and rotationsFig. 13a shows the rotation angle q (positive for an outwardtilting) measured during backfilling and surcharging of CWs. Therotation angle (q) was calculated based on two simultaneousequations (with two measured horizontal displacements fromtransducers, DW1 and DW3) which are functions of two unknowns(the translational displacement, Dh and q). The abscissa in Fig. 13aisthe equivalent backfill height (He) defined by:He ¼ Hb þ q=g (1)Hb: height of backfill (0 Hb H).Fig. 13a shows that for He 0.8 H, counter clockwise rotationsincrease with increasing He/H, up to a certain value of He/H,depending on the deformability of foundations. After that, a tilt-ing-forward mode becomes dominant and some of the walls(the one with kv ¼ 1.8 and 3.6 kPa/mm) reached a state of totalcollapse. Only the case of kv ¼ 1.3 kPa/mm remained in the stateof negative rotation angle (tilting-backward state). Thus, themodes of rotation of the wall are both ground-stiffness andbackfill height dependent. The measured rotation angles for GRS-BWs are shown in Fig. 13b. The values of q for He < 0.8 H are notavailable because the facing of GRS-BW was stacked progressivelywith rising backfill. Fig. 13b shows that relatively stable conditionscan be obtained in the case of GRS-RW both during backfillingand surcharging in the sense that values of q observed in thesefour cases are small in both magnitude and variation. In general,GRS-BWs performed better than CWs in tolerating foundationsettlement, and a threshold value of kv ¼ 1.8 kPa/mm whichgenerates a critical state of the wall (in terms of q) exists for bothCWs and GRS-RWs.Figs. 14a,b showthe horizontal outwardmovement of the facingof CWs and GRS-BWs, respectively. In the case of CW on a non-yielding foundation (kv ¼NkPa/mm), an abrupt increase in thehorizontal displacement (Dh) occurs at He j1.1 H; the thresholdvalues of He for an abrupt rise in Dh tend to increasewith decreasingkv. At the full surcharge state (Dh/H ¼ 1.5), the ground ofFig. 13. (a) Developments of wall rotation (q) during backfilling and surchargingof CWs. (b) Developments of wall rotation (q) during backfilling and surcharging ofGRS-RWs. kv ¼NkPa/mmgives theminimumDh/H. Fig.14b shows that in thecase of GRS-BW, the value of Dh is less influenced by kv, in the sensethat the values of Dh are similar for kv ¼N and 1.3 kPa/mm.Comparing the cases of CW and GRS-BW for kv ¼ 1.8 kPa/mm,relatively large values of Dh occur at He/H ¼ 1.5, but to a much lessextent in the case of GRS-BW. The generally smaller values of Dhobserved in the case of GRS-BWconfirm that GRS-BWoutperformsCW when placed on a yielding ground.Figs. 15a,b show the vertical settlement of the crest of thebackfill (Dv1)measured at a distance of 20 mm(¼0.04 $ H) fromthefacing for CWand GRS-BW, during surcharging. In the case of CW,an abrupt increase in the values of Dv1 can be found for kv ¼ 3.6 and1.8 kPa/mm. For the case of kv ¼ 1.8 kPa/mm, an abrupt increase inDv1 occurs at He ¼ 1.4H, associated with an excessive outwardmovement of the wall. In contrast to the behavior of CW shown inFig.15a, values of Dv1 in response to the settlement of thewall seemto bemore consistent than those observed in Fig. 15a. That is, linearrelationships between Dv1/H and He/H exist for all cases and theincreasing rate of Dv1/H increases with decreasing kv. Themaximum settlement at the crest of the backfill when subjected toa surcharge q of 17 kN/m2is Dv1 ¼0.03H, revealing the settlement-tolerating feature of GRS-BW.Figs. 16a,b compare the progressive developments of lateralpressure coefficients (Kf) measured at the back of the facing for CWand GRS-RW, respectively. Kf is defined as:Kf¼ SPhi 0:5 g H2 þ q H