Initial margin is the collateral required to open a new position or submit an order to increase the risk exposure of an existing position. If your initial margin reaches 100% (as indicated in the Balance & Margin panel as well as in the top right corner of the Thalex trading interface), it means that you are in breach of the initial margin requirement.
In that case, you will lose the ability to submit orders that would increase your overall risk exposure. Instead, you will only be permitted to enter orders that are risk reducing and any open orders that could potentially increase your risk exposure will be automatically cancelled.