Seepage Patterns in an Earth-Rock Fill Dam Evaluation using Electrical Resistivity Tomography (ERT) Method

Seepages in the earth-rock fill dam are usually monitored by pore pressure, seepage water table, and seepage discharge. However, those monitoring are difficult to describe the seepage patterns because they are installed only in certain points. This research evaluated the seepage pattern resulting from Electrical Resistivity Tomography (ERT). The resistivity was measured by installing electrodes upstream of the Dam at every 10 m and downstream at 20 m distances. The seepage pattern was analysed from the resistivity 2 Dimension distribution using the RES2DINV program. The results showed that the seepage pattern resulting from the ERT method’s resistivity data, which was compared with data of surface dam deformation, pore pressure, and seepage water table, could explain the seepage discharge data. Based on those confirming data, the resistivity data of the ERT method was appropriate to explain the seepage pattern in the earth-rock fill dam and can be further utilized for dam stability analysis.

Discovery and Early Studies of the Post-Dolmen Burial Site near Sevastopolskaya Village

The paper provides a summary of the results of early studies carried out within the archeo­logical complex near Sevastopolskaya village (the Republic of Adygea) discovered in 2019. The site includes a settlement and a dolmen-mound burial. In 2020, the archeologists studied Sevastopolsky-35 mound — a frame box under a rock fill, as well as a re-used dolmen (Sevastopolsky-41). The authors believe the discovered objects are so-called post-dolmen monuments of the Middle Bronze Age (Shushuk-I period). The objects are pre-dated 28th–24th cent. B.C.

Analisis Stabilitas Timbunan pada Tanah Dasar Berbentuk Lereng dengan Metode Elemen Hingga

ABSTRAKAnalisis menggunakan program PLAXIS 2D dengan tinggi timbunan dan kemiringan tanah dasar bervariasi tanpa dan dengan perkuatan rock fill sehingga diperoleh kebutuhan rock fill agar faktor keamanan memenuhi syarat. Hasil analisis dengan kemiringan tanah dasar 1V:8H diperoleh kebutuhan rock fill timbunan lempung dengan tinggi 5m, 10m, 15m dan 20m sebesar 0%; 24,7%; 45,5% dan 59,1% sedangkan timbunan pasir sebesar 14,5%; 43,2%; 62,4% dan 71,4%. Pada kemiringan tanah dasar 1V:6H diperoleh kebutuhan rock fill masing-masing ketinggian timbunan lempung sebesar 5%; 45,8%; 59,3% dan 66.6%, sedangkan timbunan pasir sebesar 33,1%; 62,3%; 71,9% dan 73,2%. Pada kemiringan tanah dasar 1V:4H diperoleh kebutuhan rock fill masing-masing ketinggian timbunan lempung sebesar 48,9%; 66,7%; 75,6% dan 81,3%; sedangkan timbunan pasir sebesar 60,1%; 72,6%; 80,5% dan 84%. Variasi jenis mesh menghasilkan faktor keamanan yang tidak signifikan antar jenis mesh dikarenakan lapisan timbunan yang dimodelkan relatif rapat. Analisis geometri tanah dasar bertangga dengan lurus tidak menunjukkan pengaruh yang signifikan terhadap faktor keamanan.Kata kunci: stabilitas lereng, timbunan, tanah dasar, rock fill, metode elemen hingga, PLAXIS 2D ABSTRACTAnalysis using PLAXIS 2D program with varying heights and slopes of subgrade without and with rock fill reinforcement in order to obtain the need for rock fill so that the safety factor meets the requirements. The results of the analysis with a subgrade slope of 1V: 8H obtained the need for rock fill clay pile with a height of 5m, 10m, 15m and 20m of 0%; 24.7%; 45.5% and 59.1% while the sand pile was 14.5%; 43.2%; 62.4% and 71.4%. At a subgrade slope of 1V: 6H, the required rock fill height for each clay pile is 5%; 45.8%; 59.3% and 66.6%, while the sand pile was 33.1%; 62.3%; 71.9% and 73.2%. At 1V: 4H subgrade slope, the required rock fill height for each clay pile height is 48.9%; 66.7%; 75.6% and 81.3%; while the sand pile was 60.1%; 72.6%; 80.5% and 84%. Variation of mesh types resulted in insignificant safety factor between mesh types because the modeled embankment layer was relatively tight. The geometry analysis of the straight stepped subgrade did not show a significant effect on the safety factor.Keywords: slope stability, embankment, subgrade, rock fill, Finite Element method, PLAXIS 2D