No abstract

One of the most common soft soil enhancement techniques used to expedite the consolidation time significantly is Prefabricated Vertical Drains (PVD). This technique needs a sufficient discharge capacity value because it primarily functions as a drainage channel. The deformation of PVD is considered as one of the primary factors which affect discharge capacity. Therefore, this research determined the influence of upper-side deformation on PVD's discharge capacity (qw) using a specific design apparatus known as ASTM D4716, which manages the determination of transmissivity and flow rate at the longitudinal direction of geosynthetics. Furthermore, two PVD samples with dimensions of 3 and 4 mm thickness, 100 mm width, and 1000 mm length were examined under straight and buckled conditions. Stepwise confining pressures from 50 to 200 kPa were subjected to the samples under hydraulic gradients with values of 0.2, 0.5, and 1.0. The results showed that samples with greater thickness had higher discharge capacity, which significantly reduced in the lower hydraulic gradient. The deformation on the upper side of PVD induced a decrease of discharge capacity by approximately 13-16%, which led to a delay in the consolidation time. The discharge capacity values obtained from the experiments were employed as parameters in a time factor ratio of Th,w/Th. The analysis results show that the buckled PVD has a more considerable consolidation time due to the increase in the Th,w/Th ratio, with a discharge capacity value below 10-4 m3/s. It can be concluded that the deformation in the form of buckled conditions on the upper side of PVD had a considerable impact on PVD effectiveness.

Kabupaten Magetan terletak pada posisi 7°38'30" Lintang Selatan dan 111°20'30" Bujur Timur dengan luas mencapai 688,85 km². Dengan mayoritas penduduk adalah petani. Hal tersebut sesuai dengan ketersediaan lahan pertanian yang masih luas yaitu 28.269 ha tanah sawah dan 40.616 ha tanah kering.  Meskipun pertanian menjadi lahan utama di Magetan, tetapi masih banyak desa di Magetan yang termasuk kelas kekeringan lahan tinggi. Berdasarkan kondisi tersebut, maka untuk meningkatkan produksi pertanian, diusulkan pembuatan embung.  Tujuan kegiatan pengabdian pada masyarakat adalah untuk melakukan analisa potensi embung sebagai alternatif solusi kekeringan.  Metode yang dilaksanakan adalah dengan melakukan survei untuk mendapatkan data fisik dan non fisik yang diperlukan untuk mendukung analisa yang dilaksanakan mulai bulan mei hingga juli 2022. Data menggunakan data primer dan sekunder dari beberapa sumber. Hasil survey ditindaklanjuti dengan rapat koordinasi tim pengabdian masyarakat, dimana hasilnya menjadi bahan Focus Group Discussion (FGD). Pihak-pihak yang diundang dalam kegiatan FGD adalah perangkat desa Randugede Kecamatan Plaosan Kabupaten Magetan dan Kepala Bidang SDA DPUPR beserta stafnya. Hasil akhir kegiatan pengabdian masyarakat yaitu lebih menyarankan untuk pengembangan embung di lokasi Desa Randugede sisi bawah karena kontur lebih memungkinkan untuk pembuatan embung dibandingkan dengan sisi atas.Magetan Regency is located at 7°38'30" south latitude and 111°20'30" east longitude with an area of 688.85 km². The majority of the population is farmers. Consequently, this location is to the availability of agricultural land, which is still extensive such as 28,269 ha of harvest fields and 40,616 ha of drought land. Although agriculture is the principal land in Magetan, many villages in Magetan still belong to high land drought susceptibility. It should build a reservoir based on these conditions to increase agricultural production. This paper aims to analyze the potential of reservoirs as an alternative solution to drought. The method implemented is to survey to obtain physical and non-physical data needed to support the analysis. The data uses primary and secondary data from several sources. The survey results were followed up with a team coordination meeting, where the results were used as a Focus Group Discussion (FGD). The parties invited to the FGD activities were the Randugede, Plaosan District, Magetan Regency, and the Head of the DPUPR. The final result of community service activities is more advisable to develop a reservoir at the Randugede Village location on the bottom side because the contours are more likely to build a pond than the top side.

Jurnal berisikan analasisis perbandingan antara hasil analisis penggunaan Prefabricted Vertical Drains (PVD) di tanah lunak menggunakan metode konvensional Hansbo (1979) dan hasil pemodelan dengan Sigma W GeoStudio dengan model tanah lunak menggunakan linear elastic. Kondisi yang dianalisis kondisi tanah lunak dengan beban timbunan di atasnya tanpa adanya perbaikan, kondisi kedua dengan PVD tanpa memperhitungkan efek smear zone, dan dengan PVD dengan memperhitungkan efek smear zone.  Hasil analisis berupa grafik hubungan besaran penurunan dengan waktu yang diperlukan. Hasil dengan pemodelan software memiliki variasi deformasi pada tanah akibat beban yang bekerja, dengan pola waktu yang diperlukan untuk mencapai derajat konsolidasi (U) 90%. Pola waktu yang diperoleh dari ketiga kondisi dan deformasi yang dihasilkan dapat dilakukan perbandingan kedua analisis.

Prefabricated Vertical Drains (PVD) has become a standard method in soft soil improvements project to accelerate the soil consolidation time. Due to PVD's primary function as drainage, it should have adequate hydraulic properties, i.e., discharge capacity and transmissivity. This paper evaluates the effect of incremental confining pressure on three types of PVD using an apparatus adopting ASTM D4716, a mechanism to determine the in-plane flow rate and transmissivity of geosynthetics. The apparatus is originally designed to observe the discharge capacity of the PVD. Three types of PVD with different thickness and box channel core shapes were tested under incremental confining pressure in the range of 50 to 200 kPa and varied hydraulic gradients. The results indicated that the reduction of discharge capacity under incremental confining pressure is higher for lower hydraulic gradients, and the reduction of discharge capacity is significant at high confining pressure. The thickness of PVD held an essential role in transmissivity since PVD with greater thickness provides higher discharge capacity and transmissivity.